Answers
Answer:
Explanation:
Here, we want to get the valence electron number for each of the listed elements
The number of valence electrons is used to put elements into groups
Thus, an element will have 1 valence electron if it belongs to group 1
Now, let us get the valence electrons for each of the listed elements
Carbon C has 6 valence electrons
Chlorine Cl has 7 valence electrons
Neon Ne has 8 valence electrons
Calcium Ca has 2 valence electrons
Oxygen O has 6 valence electrons
Kindly note that we do not count the d-block when checking for the number of valence electrons. After the second group, we skip the next 10 (the transition metals) and count the next group, starting from Boron as 3, in that sequence
Related Questions
If something is made of 2.1 g Ni and 0.58 g O, what is the empirical formula?
Answers
To know the empirical formula we will determine how many moles of each element we have. To do this, we must look up in the periodic table the atomic weight of each element.
The atomic weight of Ni = 58.6934 g/mol
O = 15.999 g/mol
Now we divide the mass of each element by its atomic weight to determine how many moles are in the sample.
[tex]\begin{gathered} \text{Mol of Ni = }\frac{\text{Mass of Ni}}{\text{Atomic weight}} \\ Mol\text{ of Ni = }\frac{\text{2.1 g}}{58.6934\text{ g/mol}}=0.036\text{ mol of Ni} \end{gathered}[/tex][tex]\begin{gathered} \text{Mol of O = }\frac{Mass\text{ of O}}{\text{Atomic weight}} \\ \text{Mol of O = }\frac{0.\text{58 g}}{15.999\text{ g/mol}}=\text{ 0.036 mol of O} \end{gathered}[/tex]In the sample, there are 0.036 moles of oxygen and 0.036 moles of Ni. The ratio is 1 to 1, so the empirical formula will be: NiO
What is the concentration if I have 450 mL of iron (II) chloride (FeCl2) solution that contains9.6 grams of iron (II) chloride solute?
Answers
0.168M
Explanations:The formula for calculating the concentration of the solution is expressed as:
[tex]concentration=\frac{mole}{volume}[/tex]Determine the moles of iron(II) chloride
[tex]\begin{gathered} mole\text{ of FeCl}_2=\frac{9.6g}{126.751g\text{/}mol} \\ mole\text{ of FeCl}_2=0.0757moles \end{gathered}[/tex]Given that volume is 0.45L, hence the concentration is expressed as:
[tex]\begin{gathered} concentration=\frac{0.0757}{0.45} \\ concentration=0.168M \end{gathered}[/tex]Hence the concentration of the solution is 0.168M
Which of the following describes a unique property of water that helps sustain marine life? It freezes upward from the bottom unlike other liquids that freeze downward from the top. It has a lower density in its solid state than it does in its liquid state. It shows changes in density at temperatures above 4 °C. It cools faster and heats up faster than most other liquids.
Answers
Answer:
It has a lower density in its solid state than it does in its liquid state
Explanation:
Here, we want to get the unique property of water that helps sustain marine life
As we know, the marine environment consists of several zones with different states. However, it is necessary that aquatic lives are supported in all zones.
In cases where we have a solid state of water, which is ice, aquatic organisms are expected to thrive. Now, the density of water matters in these states.
The density of water is lower in the solid state than in the liquid state, which is unusual for most other liquids. This unique property ensures the sustenance of aquatic lives
Calculate the final concentration of a solution created through the following process: 1.7L of a 2.4 M NaF solution is diluted with water to 3.3 L of NaD solution.
Answers
The final concentration when 1.7L of a 2.4 M NaF solution is diluted with water to 3.3 L is 1.24 M
Calculating final concentration of solution :
For calculating the final concentration when 1.7L of a 2.4 M NaF solution is diluted with water to 3.3 L we use below given formula
[tex]M_{1} V_{1}[/tex]= [tex]M_{2} V_{2}[/tex]
Where,
[tex]M_{1}[/tex]= 2.4 M
[tex]V_{1}[/tex]= 1.7 L
[tex]M_{2}[/tex]= 'X' to be calculated
[tex]V_{2}[/tex]= 3.3L
(2.4)*1.7=X*3.3
X= 2.4*1.7/3.3
X= 1.24 M
How to calculate concentration ?Divide the solute's mass from the total volume of the solution. Using m as the solute's mass and V as the total volume of the solution, write out the equation C = m/V.
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There are four sketches below. The first sketch shows a sample of Substance X. The three sketches underneath it show three different changes to the sample.
You must decide whether each of these changes is possible. If a change is possible, you must also decide whether it is a physical change or a chemical change.
Each sketch is drawn as if the sample were under a microscope so powerful that individual atoms could be seen. Also, you should assume that you can see the
entire sample, and that the sample is in a sealed box, so that no matter can enter or leave.
Sample of Substance X
oli
Change 1
Change 2
Change 3
Change 1 is:
Impossible
a physical change
Change 2 is:
Impossible
a physical change
Change 3 is
Impossible
a physical change
Explanation
Check
Answers
Physical change: a new substance is not produced.
Chemical change: produces a new substance.
The substance x has one white dot, two black dots and one white again.
W - B - B - W.
If we look at the change 1 we can see that we have one green, two black and another green.
Is it possible to have one green atom? What does that mean? It means that we have another atom there. The problem says that the sample is in a sealed box, so that no matter can enter or leave. So in my opinion the first one is impossible.
In the second change I can't decide between physical and chemical. I think it is a chemical change because there is a rearrengement.
In the third change there are 12 molecules, Each molecule has two black atoms and 4 white atoms. In the substance x only had 24 white atoms, but in the change 3 we have 48 white atoms. As we said before the sample is in a sealed box, so that no matter can enter or leave. So it also impossible.
If 15.2g of aluminum reacts with 39.1g of chlorine, how many g of AlCl3 forms?
Answers
Answer:
74.9g of AlCl3 are formed.
Explanation:
1st) It is necessary to write and balance the chemical reaction:
[tex]2Al+3Cl_2\rightarrow2AlCl_3[/tex]From the balanced reaction, we know that 2 moles of Al react with 3 moles of Cl2 to produce 2 moles of AlCl3.
2nd) With the molar mass of Al and Cl2, we can convert the moles to grams:
- Al molar mass: 27g/mol
- Al conversion:
[tex]2moles*\frac{27g}{1mole}=54g[/tex]- Cl2 molar mass: 71g/mol
- Cl2 conversion:
[tex]3moles\frac{71g}{1mole}=213g[/tex]Now we know that from the balanced reaction, 54g of Al react with 213g of Cl2.
3rd) Now we have to find out which compound is the limiting reactant and which compound is the excess reactant:
[tex]\begin{gathered} 54gAl-213gCl_2 \\ 15.2gAl-x=\frac{15.2gAl*213gCl_2}{54gAl} \\ x=59.96gCl_2 \end{gathered}[/tex]Now we know that the 15.2g of Al will need 59.96g of Cl2, but we only have 39.1g of Cl2, so Cl2 is the limiting reactant and Al is the excess reactant.
4th) With the molar mass of AlCl3, we can convert the moles to grams of AlCl3:
- AlCl3 molar mass: 133g/mol
- AlCl3 conversion:
[tex]2moles*\frac{133g}{1mole}=266g[/tex]266g of AlCl3 are formed from the balanced reaction.
5th) Finally, with the limiting reactant and the grams of AlCl3 that must be produced from the balanced reaction, we can calculate the grams of AlCl3 that will be formed from 15.2g of aluminum:
[tex]\begin{gathered} 54gAl-266gAlCl_3 \\ 15.2gAl-x=\frac{15.2gAl*266gAlCl_3}{54gAl} \\ x=74.9gAlCl_3 \end{gathered}[/tex]So, 74.9g of AlCl3 are formed.
Which of the following results in a new substance being formed?-Physical Change-Physical Property-Chemical Change-Chemical Property
Answers
Answer
Chemical change
Explanation
Chemical changes occur when a substance combines with another to form a new substance,
How will you describe the pattern as electrons are distributed
Answers
How will you describe the pattern as electrons are distributed?
In a simple way, you can say, electrons are arranged around an atom's nucleus.
When electrons are near the nucleus, have the lowest energy. Electrons further aways will have higher energy.
We can say electrons are in different shells with different energy. Inside those shells, electrons are in subshells too.
Then you have some numbers that describe the completly characteristics of an electron in an atom.
They are called Quantum Numbers. They are four
1) The principal Quantum number (n): describes the energy of an electron and the most probable distance of the electron from the nucleus. In other words, it refers to the size of the orbital and the energy level an electron is placed in.
2) The number of subshells or (l): describes the shape of the orbital. It can also be used to determine the number of angular nodes.
3) The magnetic Quantum number (ml): describes the energy levels in a subshell. (Remember we have shells and inside of them we have subshells)
4) The Spin of the Electron (ms): refers to the spin of the electron which can either be up or down.
[tex]_{m_{s\text{ }}}[/tex]Which of the following best describes an ecosystem in the Great Lakes?
Answers
The statement " all the living organisms in an area and their physical surroundings " will describes an ecosystem in the Great Lakes.
A biological combination of cooperating organisms and surrounding physical environment can be referred to as an ecosystem.
A system made up of biotic and abiotic elements that work together as a whole is called an ecosystem. All live things are considered to be biotic components, although non-living items are considered to be abiotic components.
Therefore, "all the living organisms in an area and their physical surroundings " will define ecosystem in the Great Lakes.
The given question is incomplete. The complete question is
Which of the following best describes an ecosystem?
A. all the living organisms in an area
B. all the living organisms in an area and their physical surroundings
C. a region with a distinct climate
D. all the living organisms of the same species throughout the world
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How many moles of NaOH are in 21.4 mL of 1.29 M NaOH?
Answers
Answer:
n = 0.0276 mol
Explanation:
Required: Moles of NaOH
Given:
Volume of NaOH = 21.4 mL
Molarity/concentation = 1.29 M
Solution:
We will use the following equation to solve the problem:
[tex]C\text{ =}\frac{n}{V}[/tex]C is the concentration or molarity in mol/L or M, n is the number of moles in mol and V is the volume in L. Therefore we need to first convert mL to L.
1mL = 0.001 L
therefore 21.4 mL = 0.0214 L
Lets re-arrange the equation:
n = CV
n = 1.29 mol/L x 0.0214 L
n = 0.0276 mol
Lakeshea analyzed 6.234 grams of a substance and found it to be composed of 4.980 g of carbon and 1.254 g of hydrogen. In the next lab group, Niles analyzed another sample of the same substance and found 4.004 g of carbon.
A) How much hydrogen did Niles find in his sample
B) What is the justification(what law: Conservation of mass, Definite Proportions, Multiple Proportions) for your answer?
Answers
Lakeshea analyzed 6.234 grams of a substance and found it to be composed of 4.980 g of carbon and 1.254 g of hydrogen. Niles analyzes another sample of the same substance containing 4.004 g of carbon. A) hydrogen did Niles find in his sample is 2.23 g. B) The justification is the law of conservation of mass.
According to the law of mass of conservation of mass : mass neither be created nor be destroyed. so, that if sample is of 6.234 g contain 4.980 g carbon and 1.254 g hydrogen then the same sample if contain 4.004 g of carbon then the hydrogen will be 2.23 g of hydrogen.
Thus, Lakeshea analyzed 6.234 grams of a substance and found it to be composed of 4.980 g of carbon and 1.254 g of hydrogen. Niles analyzes another sample of the same substance , containing 4.004 g of carbon. A) hydrogen did Niles find in his sample is 2.23 g. B) The justification is the law of conservation of mass.
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A sample of liquid ethanol is added to a sealed glass beaker.A sealed beaker contains liquid ethanol, represented as circles. Most of the circles are in the liquid, but a few are in the space above the liquid.Figure © 2019 StrongMindBeaker: BlueRingMedia/ShutterstockWhat will happen to the ethanol after a minute?
Answers
We don't have information about how fast the equilibrium will be reached, however, we can analyze the options to see which ones are wrong.
What in fact happens is that the system's previous conditions doesn't matter much. After it is sealed, there is no way something gets out. At first, the system will not be at an equilibrium, it needs some time for that.
The system will have ethanol gas condensating and liquid ethanol evaporating, but at different rates.
Assuming the rate of evaporation is higher at the beginning, we will get more ethanol gas with time, but this will decrease the rate of evaporation a situation where both rates are equal. After that point, the system will be at equilibrium, meaning the amount of liquid and gas won't change anymore.
Having that in mind, the first alternative have the first part wront because the system nees time to get to equilibrium, but its second part is wrong too, because as we said the system will eventually stop getting more ethanol gas.
The second is wrong because both evaporating and condensation are happening at the same time, not one after the other.
The third is wrong because it wil always have an equilibrium. If all ethanol condensates, the rate of condensation will be zero and any evaporation that happens will make some ethanol gas back.
We can't know for sure that 1 minute will be enough to reach the equilibrium, but assuming it is, the fourth alternative perfectly describes what is happening: ethanol condensates and increase the pressure up to a point where both rates equilizes and the system reach the equilibrium.
So, the correct option is the fourth alternative.
what type of reaction is Propane + O2 - Co2 + H2O
Answers
Answer: This is a perfect example of a combustion reaction because we have a carbon based compound reaction with oxygen gas to produce carbon dioxide and water. Hopefully this helps!
Explanation:
What volume of hydrogen gas is evolved from a reaction between 0.52 g of Na and water? The gas is collected at 25°C and 740 mmHg.___ Na (s) + ___ H2O (l) → ___NaOH (aq) + ___ H2 (g)
Answers
0.284L
ExplanationsThe balanced chemical reaction between sodium and water is expressed as:
[tex]2Na(s)+2H_2O(l)\rightarrow2NaOH(aq)+H_2(g)[/tex]Determine the moles of sodium Na that reacted
[tex]\begin{gathered} moles\text{ of Na}=\frac{mass}{molar\text{ mass}} \\ moles\text{ of Na}=\frac{0.52}{23} \\ moles\text{ of Na}=0.0226moles \end{gathered}[/tex]Based on stoichiometry, 2moles of sodium produces 1 mole of hydrogen gas. The moles of hydrogen gas required is given as:
[tex]\begin{gathered} mole\text{ of H}_2=\frac{1}{2}\times0.0226 \\ mole\text{ of H}_2=0.0113moles \end{gathered}[/tex]According to the ideal gas equation
[tex]\begin{gathered} PV=nRT \\ V=\frac{nRT}{P} \end{gathered}[/tex]Given the following
P = 740mmHg = 0.974atm
T = 25 +273 = 298K
R = 0.08205 Latm/molK (Gas constant)
Substitute the given parameters into the formula to have:
[tex]\begin{gathered} V=\frac{0.0113\times0.08205\times298}{0.974} \\ V=\frac{0.2764}{0.974} \\ V=0.284L \end{gathered}[/tex]Hence the volume of hydrogen gas that evolved from the reaction is 0.284L
A person has a sample of gas with a volume of 9.02L and a temperature of 585.57k. If the volume of the container is reduced to 2.24L, what will the new temperature of the gas be in Kelvin?
Answers
Step 1 - Understanding the relation between volume and temperature for a gas sample
There are three main variables that can change the state of a gas sample: temperature, pressure and volume. If the pressure (P) is kept constant, the volume (V) becomes proportional to the temperature (T) in K:
[tex]\frac{V_1}{T_1}=\frac{V_2}{T_2}[/tex]Step 2 - Substituting the values in the equation above
We know, from the exercise, that V1 = 9.02 L and T1 = 585.57 K, and V2=2.24 L. Substituting these values in the equation above:
[tex]\begin{gathered} \frac{9.02}{585.57}=\frac{2.24}{T_2} \\ \\ T_2=\frac{2.24\times585.57}{9.02}= \end{gathered}[/tex]When the combustion engine was invented it had many positive effects on society. In 1938
scientists concluded that burning fossil fuels would cause which disastrous effect to the
environment?
A. climate change
B. the ozone layer to dissipate
C. increased deforestation
D. increased flooding
Answers
answer: The burning of fossil fuels leads to climate change so the correct answer is option D
Explanation: Burning fossil fuels releases a large amount of co2 into the atmosphere. C02 is a greenhouse gas so it traps the sun's heat this, in turn, heats up our atmosphere which leads to climate change.
now option B is wrong because the ozone layer is depleted due to ozone-depleting substances which when it comes to contact with ozone damage it and option c is due to human activities
finally, option d is due to climate change and this is an indirect effect of burning fossil fuels.
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convert 8 mol Na to grams
Answers
184g
Explanations:The formula for calculating the mass of a substance is expressed as;
[tex]moles=mass\times molar\text{ mass}[/tex]Given the following parameters
• Moles of Na = 8moles
,• Molar mass of Na = 23g/mol
Substitute the given parameter into the formula
[tex]\begin{gathered} Mass\text{ of Na}=moles\times molar\text{ mass} \\ Mass\text{ }of\text{ Na}=8moles\times\frac{23g}{mol} \\ Mass\text{ of Na}=184g \end{gathered}[/tex]Hence the mass of the sodium is 184g
Why wouldn’t an electrolyte conduct electricity in the solid form?
Answers
Answer
When the electrolyte is in solid state, electrons are tightly bound to the atoms and are not easily available to flow. So, they do not conduct electricity well.
What mass of oxygen is needed to burn 54.0 g of butane
Answers
Answer
The mass of oxygen needed to burn 54.0g of butane is 193.24 g
Explanation
Given:
Mass of butane = 54.0 g
What to find:
The mass of oxygen needed to burn 54.0g of butane.
Step-by-step solution:
Step 1: Write the balanced chemical equation for the reaction.
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
Step 2: Convert 54.0 g of butane to moles
Molar mass of C₄H₁₀ = 58.12 g/mol
[tex]Moles=\frac{Mass}{Molar\text{ }mass}=\frac{54.0\text{ }g}{58.12\text{ }g\text{/}mol}=0.9291\text{ }mol[/tex]Step 3: Use the mole ratio in step one and the mole of C₄H₁₀ in step 2 to calculate the mole of oxygen.
[tex]\begin{gathered} 13\text{ }mol\text{ }O_2=2\text{ }mol\text{ }C_4H_{10} \\ \\ x=0.9291\text{ }mol\text{ }C_4H_{10} \\ \\ x=\frac{0.9291\text{ }mol\text{ }C_4H_{10}}{2\text{ }mol\text{ }C_4H_{10}}\times13\text{ }mol\text{ }O_2 \\ \\ x=6.03915\text{ }mol\text{ }O_2 \end{gathered}[/tex]Step 4: Convert the moles of O₂ in step 3 to mass in grams.
Molar mass of O₂ = 31.998 g/mol
[tex]\begin{gathered} Mass=Moles\times Molar\text{ }mass \\ \\ Mass=6.03915mol\times31.998g\text{/}mol \\ \\ Mass=193.24\text{ }g\text{ }of\text{ }O_2 \end{gathered}[/tex]Hence, the mass of oxygen needed to burn 54.0g of butane is 193.24 g
A 10 L cylinder of gas is stored at room temperature (25 Celsius) and a pressure of 1800 psi. if the gas is transferred to a 6.0 L cylinder, at what temperature would it have to be stored in order for the pressure to remain at 1800 psi?
Answers
Since we want the pressure to remain constant we have to use Charles Law of gases, that relates the volume and the temperature at a constant pressure:
[tex]\frac{V1}{T1}=\frac{V2}{T2}[/tex]In this case, we know the values of V1, T1 and V2, which are 10L, 25°C and 6.0L. Using these values we have to find T2:
[tex]\begin{gathered} T2=\frac{V2\cdot T1}{V1} \\ T2=\frac{6.0L\cdot25}{10L} \\ T2=15 \end{gathered}[/tex]The gas has to be stored at 15°C.
How many grams of NaOH are needed to make 100 ml of a 1 M solution? (numbers only, to the nearest 0.1)
Answers
ANSWER
The mass of NaOH in grams is 4.0 grams
EXPLANATION
Given data
The volume of the solution = 100 ml
The molarity of the solution = 1 M
To find the mass of NaOH in grams. follow the steps below
Step 1: Find the number of moles by applying the molarity formula
[tex]n\text{ = C}\times v[/tex]Where
n = the number of moles
C = Concentration in molarity
v = volume of the solution in liters
Step 2:convert the volume of the solution from ml to l
[tex]\begin{gathered} \text{ 1ml is equivaent to 0.001l} \\ Hence,\text{ } \\ 100ml\text{ = 100 }\times\text{ 0.001} \\ 100ml\text{ = 0.1l} \end{gathered}[/tex]Step 3: substitute the given data into the formula in step 1
[tex]\begin{gathered} n\text{ = cv} \\ n\text{ = 1 }\times\text{ 0.1} \\ n\text{ = 0.1 mol} \end{gathered}[/tex]Hence, the number of moles of NaOH is 0.1 mol
Step 4: Find the mass in grams by using the below formula
[tex]\text{ Mole = }\frac{\text{ mass}}{\text{ molar mass}}[/tex]Recall, that the molar mass of NaOH is 39.997 g/mol
Step 5: substitute the given data into the formula in step 4
[tex]\begin{gathered} \text{ Mole = }\frac{\text{ mass}}{\text{ molar mass}} \\ 0.1\text{ = }\frac{mass}{39.997} \\ cross\text{ multiply} \\ mass\text{ = 0.1 }\times\text{ 39.997} \\ \text{ Mass = 3.997 grams} \\ \text{ Mass}\approx\text{ 4.0 grams} \end{gathered}[/tex]Hence, the mass of NaOH in grams is 4.0 grams
neutral atoms contain equal numbers of
Answers
Answer:
protons and electrons
Explanation:
Name the type of reaction below:
CaO + H2O →Ca(OH)2
Answers
CaO and H2O mix to form Ca(OH)2, a single chemical. It is a combination reaction as a result.
What is combination reaction ?When two or more elements or compounds combine to create a single product, the reaction is known as a direct combination reaction. Equations of the type X + Y. XY are used to depict these reactions.
A combination reaction occurs when two or more components combine to produce a single compound.
Combination reactions occur when two or more reactants come together to create a new product. Synthesis reaction is another name for combination reaction. For instance, hydrogen and chlorine can mix to form hydro-chloride.
Thus, CaO + H2O →Ca(OH)2 this reaction is combination reaction.
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Consider a gas at (3.420x10^2) kPa in a (7.6100x10^-1) L container at (1.8000x10^1)°C. What will thpressure of the gas be. if it is released into a room with a volume of (1.91x10^4) L and a temperature(1.3000x10^1)°C? Express your answer to three significant digits.
Answers
Answer
P2 = 9.84x10^-3 kPa
Explanation
Given:
Pressure 1 = 3.420x10^2 kPa
Volume 1 = 7.6100x10^-1 L
Temperature 1 = 1.8000x10^1 °C
Volume 2 = 1.91x10^4 L
Temperature 2 = 1.3000x10^1°C
Required: To calculate Pressure 2
Solution
We will use the combined gas law to solve this problem
[tex]\frac{P_1V_1}{T_1}\text{ = }\frac{P_2V_2}{T_2}[/tex]Re-arrange to make the subject P2:
P2 = P1V1T2/V2T1
P2 = (3.420x10^2 x 7.6100x10^-1 x 1.3000x10^1)/(1.91x10^4 x 1.8000x10^1)
P2 = 9.84x10^-3 kPa
What is the phase of water at 0.25 atm and 0°C?A. GasB. Solid and liquidC. Solid and gasD. Solid
Answers
Explanation:
We have to find the phase of water at 0.25 atm and 0°C. If we look at the phase diagram of water and throw the lines we will find that the phase of water at those conditions is solid.
Answer: d. Solid
I have 5 questions that need help to answer 1) What are covalent bonds and how do they form ? 2) How do you know which elements and how many of each are in a compound ?
3) How can you find how many valence electrons an atom has ?
4) How many valence electrons do atoms need to be happy? Which elements are the exceptions?
Answers
A covalent bond is one that is formed by two non-metal elements that, due to their low electronegativity difference, neither has the energy to steal the electrons from the other, so they share electrons with each other.
Covalent bonds form when the electronegativity difference between two elements is less than 1.7. In addition, the number of elements must be such that by sharing their electrons, all elements comply with the octet rule, that is, each element shares and completes 8 valence electrons.
If the initial concentration of a 400 ml solution is 7% and the solution is diluted down to a concentration of 4.5%, what will the new volume of the solution be?
Answers
We have that the dilution equation of concentrated solutions will be equal to:
[tex]C_1V_1=C_2V_2[/tex]where,
C1 is the initial concentration of the solution = 7%
V1 is the initial volume = 400mL
C2 is the final concentration = 4.5%
V2 is the final volume = ?
We clear Ve and replace the known data:
[tex]\begin{gathered} V_2=\frac{C_1V_1}{C_2} \\ V_2=\frac{7\%\times400mL}{4.5\%}=622mL \end{gathered}[/tex]Answer: the new volume of the solution will be 622 mL
4 N2H3CH3 (l) + 5 N2O4 (l) →12 H2O(g) + 9 N2(g) + 4 CO2 (g)The enthalpy of formation for liquid methylhydrazine is +53 kJ/mol and the enthalpy of formation for liquid dinitrogen tetroxide is -20 kJ/mol. Calculate ∆H° for this reaction, ignore significant digits for this question.
Answers
Answer
[tex]\Delta H_{rxn}\operatorname{\degree}=-4791.6\text{ }kJ\text{/}mol[/tex]Explanation
The given chemical equation for the reaction is:
[tex]4N_2H_3CH_3(l)+5N_2O_4(l)\text{ }→\text{ }12H_2O\left(g\right)+9N_2\left(g\right)+4CO_2(g)[/tex]From the given table and question, the enthalpies of formation of the reactants ad products are:
[tex]\begin{gathered} ∆H_f°(N_2H_3CH_{3(l)})=+53\text{ }kJ\text{/}mol \\ \\ ∆H_f°(N_2O_{4(l)})=-20\text{ }kJ\text{/}mol \\ \\ ∆H_f°(H_2O_{(g)})=-258.8\text{ }kJ\text{/}mol \\ \\ ∆H_f°(N_{2(g)})=0\text{ }kJ\text{/}mol \\ \\ ∆H_f°(CO_{2(g)})=-393.5\text{ }kJ\text{/}mol \end{gathered}[/tex]The ∆H° for this reaction can be calculated using the formula below:
[tex]\Delta H_{rxn}\degree=ΔH_f^{\degree}(products)-ΔH_f^{\degree}(reactants)[/tex]Put the each enthalpy of formation of the reactants and the products into the formula:
[tex]\begin{gathered} \Delta H_{rxn}\degree=[12(-258.8)+9(0)+4(-393.5)]-[4(+53)+5(-20)] \\ \\ \Delta H_{rxn}\degree=[-3105.6+0-1574]-[212-100] \\ \\ \Delta H_{rxn}\degree=-4679.6-112 \\ \\ \Delta H_{rxn}\degree=-4791.6\text{ }kJ\text{/}mol \end{gathered}[/tex]Therefore, the ∆H° for this reaction is -4791.6 kJ/mol.
Please please help please please help me please please help
Answers
A single bond is made up of 1.0 sigma bond and no pi bonds.
Pi bonds appears from double bonds onwards.
How many moles of hydrogen gas are present in a 50.0 L steel container if the pressure is at 10.0 ATM and the temperature is 27.0 C(R=.0821atm/mole-k)
Answers
• We are given the following :
P = 10 Atm
V= 50 L
R=0.0821atm/mole-k)
T= 27°C = 273.15 + 27°C = 300 .15 K = 300K
• We will use the following formula in order to find moles of hydrogen gas
PV = nRT
n = PV /RT
=( 10 * 50 )/ ( 0.0821 * 300)
n = 500/24.63
n = 20.3 moles
Therefore ; moles of hydrogen gas present = 20.3 moles