Half life is the time period in which half of the initial amount of an element will decay into a new element due to instability. For I-131, the half life is 8 days.
From 200 to 25 grams, let's see how many half lives are there:
200g -> 100g
100g -> 50g
50g -> 25g
Therefore for 200g of I-131 reach 25 grams, 3 half lives are necesseray, 3 half lives or 24 days
How many grams of water are produced in this reaction# 14
answer
13. the molar mass of O2 is 32 g/mol
conversion: 2 mols x 16 g/mol = 32 g
14. there are 2 mols of water produced and this equals:
2 mols x 18 g/mol = 36 g
A student spends 4.5 hours studying for a test. How much time is this equivalent to in seconds? 16,200 seconds 270 seconds 6,480 seconds 2,700 seconds
Answer
16,200 seconds
Explanation
Conversion factor:
1 hour = 60 minutes
1 minute = 60 seconds
Therefore,
4.5 hours x 60 minutes/1 hour = 270 minutes
270 minutes x 60 seconds/1 minute = 16,200 seconds
Describe how you can determine the total change in enthalpy and activation energy from the diagram, and if each is positive or negative.
In this diagram, we have a reaction occurring and 3 letters that represent Reactants, Activation Energy and Products. To determine which is which, first, we will almost always have the Activation Energy in the middle of the reaction, this is how much energy is required for the reaction to occur, therefore Activation Energy is represented by letter B
To determine the total change in enthalpy, we need to subtract the sum of all the enthalpy from the products, which is letter C, and the sum of all the enthalpy from the reactants, which is letter A
ΔH = C - A
In this graph, we have the energy increasing and more energy on the products side, this means that an input of energy was required, this is the description of an Endothermic reaction, therefore the sign will be Positive
How are fiber optic cables and traditional, metal-based wires similar and different?
Both fiber optic and metal are used to transmit signals across long distances. While fiber optic cables use light to carry signals making them much faster and higher quality.
3.Discuss the four macromolecules that occur in nature, including the building block units of each different macromolecule.
So,
Living things are made of four types of molecules, known as macromolecules. These macromolecules are:
1. Carbohydrates:
Carbohydrates, are sugar molecules. Along with proteins and fats, carbohydrates are one of three main nutrients found in foods and drinks. Your body breaks down carbohydrates into glucose. Glucose, or blood sugar, is the main source of energy for your body's cells, tissues, and organs. The building blocks units of Carbohydrates are called Monosaccharides, which are simple sugars. The next one is a picture that shows the structures of some Carbohydrates:
2. Lipids:
A lipid is any of various organic compounds that are insoluble in water. They include fats, waxes, oils, hormones, and certain components of membranes and function as energy-storage molecules and chemical messengers. The building block units of lipids are Fatty acids and glycerol.
We can see some structures for lipids below:
3. Proteins:
Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body's tissues and organs.
A protein is a naturally occurring, extremely complex substance that consists of amino acid residues joined by peptide bonds. Proteins are present in all living organisms and include many essential biological compounds such as enzymes, hormones, and antibodies as well. The building block units of proteins are called Aminoacids.
A protein has four structures shown below:
And, finally:
4. Nucleic acids:
Nucleic acids are naturally occurring chemical compounds that serve as the primary information-carrying molecules in cells.
They play an especially important role in directing protein synthesis. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
The building block units of nucleic acids are called Nucleotides.
The next one is their structure:
a mixture of helium,nitrogen,and oxygen has a total pressure of 723 mmHg. the partial pressure of helium is 194 mmHg, and the partial pressure of nitrogen is 262 mmHg. what is the partial pressure (in mmHg) of oxygen in the mixture
Answer:
267 mmHg.
Explanation:
What is given?
Total pressure = 723 mmHg
Partial pressure of helium (He) = 194 mmHg.
Partial pressure of nitrogen (N) = 262 mmHg.
Step-by-step solution:
Let's see the formula of total pressure:
[tex]P_{TOTAL}=P_1+P_2+...[/tex]Let's write the formula to our context if we have 3 different gases:
[tex]P_{TOTAL}=P_{He}+P_{Ni}+P_O.[/tex]We want to find the partial pressure of oxygen (O), so let's solve for Po which is the unknown value in the formula, and replace the given data:
[tex]\begin{gathered} P_O=P_{TOTAL}-P_{He}-P_N \\ P_O=723\text{ mmHg-194 mmHg-262mmHg,} \\ P_O=267\text{ mmHg.} \end{gathered}[/tex]The partial pressure of oxygen is 267 mmHg.
A student gains 1.3 lb in two weeks. How many grams did he gain?
To answer this question we have to convert pounds to grams using a conversion factor:
[tex]1.3lb\cdot\frac{453.59g}{1lb}=589.667g[/tex]He gained 589.667g.
We have seen that the behavior of gases can be described by 4 variablestemperature, pressure, volume and number of moles. Let's study the link between thepressure and the number of moles in a situation where the other two variablesremain constant. a) Using a few sentences, equations or diagrams, clearly explainsthe relationship between pressure and the number of moles. Your answer must include the notion ofcollisions to justify a pressure change. To help you answer, think ofcomplete the following sentence: "If the number of moles increases the pressure" (directly proportional or inversely proportional?) and thenjustify your choice.b) A balloon contains 4.0 moles of gas at a pressure of 1.6atm. you leave gasout of the balloon to end up with only 3.0 moles of gas. What's the newspressure inside the balloon, assuming that the volume and temperature have notnot changed. c) You need the identity of the gas to answer the question correctlyformer. True or false? No substantiation required.
Answer and Explanation
(a) At constant temperature and volume the pressure of a gas is directly proportional to the number of moles of gas.
P = n (RT/V) where P is the pressure, n is the number of moles, R is the gas constant, T is the temperature and V is the volume
So when the pressure in increased, the volume will be decreased, meaning there will be less space in the container, this will lead to more collisions inside a container, meaning, the number of moles will be increased.
[tex]\frac{P_1}{n_1}\text{ = }\frac{P_2}{n_2}[/tex](b) Given: initial number of moles (n1) = 4.0 moles
initial pressure (P1) = 1.6 atm
Final number of moles (n2) = 3.0 moles
Required: Final Pressure (P2)
solution
P1/n1 = P2/n2
P2 = P1*n2/n1
P2 = 1.6 atm*3.0 moles/4.0 moles
P2 = 1.2 atm
What is the procedure of chemical bonding?
Answer
Chemical bonding is the process where atoms or molecules combine or bond together. A chemical bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds.
Explanation
Chemical bonding is the process where atoms or molecules combine or bond together, usually to form a new compound. The outer electron orbits or shells determine which elements or molecules combine and how well they bond together. There are several types of chemical bonding. A chemical bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds.
identifying reaction types ZN+AgNO3
The type of reaction involved in the illustration is a single displacement reaction.
What are displacement reactions?Displacement reactions are chemical reactions in which an atom displaces another atom from a participating species of the reaction. Displacement reactions could be:
Single displacement reaction: here, an atom displaces another atom from a compound participating in the reaction. The reaction follows the example: A + BC ---> AB + C. Atom A has displaced atom C from the compound BC.Double displacement reaction: Here, radicals of compounds displace one another. In other words, two compounds exchange radicals to form two new compounds entirely, such that: AB + CD --> AC + BD.When you consider this reaction: [tex]Zn + AgNO_3 -- > ZnNO_3 + Ag[/tex]. Zn displaced Ag from the compound, [tex]AgNO_3[/tex]. Thus, it is a single displacement reaction.
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An atom whose atomic number is 16 and mass number is 32 can be written as:A)sulfur-16B)sulfur-32C)Germanium-32D) germanium-46
It is necessary to use the Periodic Table of Elements to find the atom with atomic number of 16 and a mass number of 32, that is Sulfur (S).
The correct way to write it is using the mass number of the element, so sulfur can be written as sulfur-32.
Drawing the structure with all elements2-chloro-5,5-diethyloctan-4-ol
Answer
The structural formula of 2-chloro-5,5-diethyloctan-4-ol is shown below
7.0 g of nitrogen is reacted with 5.0 g of hydrogen to produce ammonia according to the chemical equation shown below. Which one of the following statements is false? N2(g) + 3 H2(g) → 2 NH3(g)options:3.5 g of hydrogen are left overAll of them are falseHydrogen is the excess reactant.Nitrogen is the limiting reactant.The theoretical yield of ammonia is 15 g.
Step 1
N2(g) + 3 H2(g) → 2 NH3(g) (must be balanced)
The limiting reactant
Data needed:
The molar mass:
For N2) 28 g/mol
For H2) 2 g/mol
For NH3) 17 g/mol
Procedure:
28 g N2 ------ 3 x 2 g H2
7.0 g N2------- X = 1.5 g H2
According to this, for 7.0 g N2, 1.5 g H2 is needed to react, but 5.0 g is provided. Therefore, H2 is the excess, and N2 is the limiting reactant
1.5 g of H2 is reacted, so 5.0 g - 1.5 g= 3.5 g are leftover
------------------
Step 2
The theoretical yield.
Procedure:
28 g N2 ------ 2 x 17 g NH3
7.0 g N2------ X = 8.5 g NH3
Answer: The theoretical yield of ammonia is 15 g. FALSE
An tank contains oxygen (O2) at a pressure of 2.29 atm . What is the pressure in the tank in terms of torr
Explanation:
One atm of pressure is equal to 760 torr. We can use this relationship to find the answer to our problem.
1 atm = 760 torr
P = 2.29 atm = 2.29 atm * 760 torr/(1 atm)
P = 1740 torr
Answer: The pressure of the tank in torr is 1740 torr.
7 Megumi goes to the doctor, complaining of fatigue. The doctor examines her and asks if she has experienced heart palpitations, muscle cramps, or tingling in her hands and feet. She denies any of these symptoms. A blood test determines that Megumi’s magnesium reading is not right. Considering her symptoms, which is MOST likely true of Megumi? A. Megumi has a magnesium inadequacy. B. Megumi has a magnesium deficiency. C. Megumi has a magnesium excess. D. Megumi has a magnesium balance.
A blood test determines that Megumi’s magnesium reading is not right considering her symptoms then the Megumi has a magnesium deficiency
Magnesium deficiency is the condition in which blood level of magnesium is lower than usual and hypomagnesemia is the medical term for this disorder and magnesium shortage is an electrolyte disruption caused by a low magnesium content in the body and it can cause a variety of symptoms and the symptoms are palpitations, poor coordination, muscular spasms, lack of appetite, personality changes and because of low magnesium level the potassium level is also deceases
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Which nonmetal element in group 17 was used long ago in war to gas and terminate the enemy?
In World War 1, Chlorine gas was used as a toxic, poisonous gas to harm and terminate enemies.
I'm supposed to balance the equation AgNO3 + (NH4)2CrO4 ---> Ag2CrO4+NH4NO3I have the skeleton down. I just don't know how to balance it. this is in double-replacement.
AgNO₃ + (NH₄)₂CrO₄ ----> Ag₂CrO₄ + NH₄NO₃
This is a double replacement equation, so there is an ion exchange. So the easiest way to balance this equation is to separate the compounds into their ions.
AgNO₃ + (NH₄)₂CrO₄ ----> Ag₂CrO₄ + NH₄NO₃
Ag⁺ + NO₃⁻ + 2 NH₄⁺ + CrO₄²⁻ ----> 2 Ag⁺ + CrO₄²⁻ + NH₄⁺ + NO₃⁻
Usually we balance the elements, but it is easier in this case to balance the ions.
AgNO₃ + (NH₄)₂CrO₄ ----> Ag₂CrO₄ + NH₄NO₃
Ag⁺: 1 Ag⁺: 2
NO₃⁻: 1 NO₃⁻: 1
NH₄⁺: 2 NH₄⁺: 1
CrO₄²⁻: 1 CrO₄²⁻: 1
Let's start balancing the ion Ag⁺, we have two ions Ag⁺ on the right and only one on the left, so we have to change the coefficient in front of AgNO₃ and write a 2 there.
2 AgNO₃ + (NH₄)₂CrO₄ ----> Ag₂CrO₄ + NH₄NO₃
Ag⁺: 2 Ag⁺: 2
NO₃⁻: 2 NO₃⁻: 1
NH₄⁺: 2 NH₄⁺: 1
CrO₄²⁻: 1 CrO₄²⁻: 1
That change balanced the ion Ag⁺, but unbalanced the NO₃⁻. We have two on the left and only one on the right. We have to change the coefficient in front of NH₄NO₃ and write a 2 there.
2 AgNO₃ + (NH₄)₂CrO₄ ----> Ag₂CrO₄ + 2 NH₄NO₃
Ag⁺: 2 Ag⁺: 2
NO₃⁻: 2 NO₃⁻: 2
NH₄⁺: 2 NH₄⁺: 2
CrO₄²⁻: 1 CrO₄²⁻: 1
And finally our equation is balanced.
Answer: 2 AgNO₃ + (NH₄)₂CrO₄ ----> Ag₂CrO₄ + 2 NH₄NO₃
Fill in the blank: Elements found in in the same vertical columns (Group 1A, 2A, etc) will share common properties. In the periodic table, the vertical columns of elements are called groups, or_________.
Answer
Elements found in in the same vertical columns (Group 1A, 2A, etc) will share common properties. In the periodic table, the vertical columns of elements are called groups, or families.
Explanation
The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.
Hence, elements found in in the same vertical columns (Group 1A, 2A, etc) will share common properties. In the periodic table, the vertical columns of elements are called groups, or families.
What are the raw materials used to make many synthetic substances? synthetic substances found in the home. List two products that contain each material.
Synthetic substances:
Synthetic fibers e.g. are made from organic synthetic high-molecular compounds and are made synthetically from raw materials such as petroleum oil or petrochemicals.
Until here the answer is: petroleum oil
At home, we can find synthetic fibers, ceramics, plastics, etc
We can find synthetic fibers (polyester, Rayon, Spandex, etc) in caps, raincoats, and ropes.
Plastic can be found in bottles, cups, etc.
Calculate the number of joules released when 75.0 grams of water are cooled from the 100°C to 27.5°C
In this question, we have a situation in which we have to use the Calorimetry formula, which is how much heat was released or absorbed (in Joules), after we had a change in temperature of a compound. The formula for this Calrimetry question is:
Q = mcΔT
Where:
Q = is energy as Heat
m = mass in grams
c = is the specific heat capacity
ΔT = the change in temperature, calculated as Final Temperature - Initial T
We have:
m = 75.0 grams
c = for water is 4.184 J/g°C
ΔT = 27.5 - 100 = -72.5°C
Now adding these values into the formula:
Q = 75 * 4.184 * (-72.5)
Q = - 22750.5 Joules, or -22.75 kJ
Hydrogen’s emission spectrum includes a line of violet light that has a frequency of 7.31 * 10^14 Hz. What is the energy (in joules) a photon of the violet light?
Explanation:
The energy of a photon of the violet light can be obtained as follows:
[tex]E\text{ = h x f}[/tex]E = energy
h = Plank's constant
f = frequency
-------
Data provided:
f = 7.31x10^14 Hz
--
Data needed:
h = 6.63x10^-34 Js
So, E = h x f = 6.63x10^-34 Js x 7.31x10^14 Hz = 4.85x10^-19 J
Answer: 4.84x10^-19 J (nearest value)
In the equation:2H2 + O2 → 2H2O100 molecules of hydrogen react with ........... molecules of oxygen.
Answer:
[tex]50\text{ molecules}[/tex]Explanation:
Here, we want to know the number of molecules of oxygen that was reacted with
From the question, we can see that the mole ratio is 2 to 1
Thus, the number of molecules of oxygen reacted will be half that of hydrogen
Hence, the number of molecules of oxygen will be:
[tex]\rightarrow\frac{100}{2}\text{ = 50 molecules}[/tex]Question 5 of 12SubmitWhich one of the following is an example of the First Law of Thermodynamics?A) As time passes, your room becomesmessier unless you spend energy to clean it.B) Water will only become ice if it is in a verycold environment.C) When a combustion reaction producesheat, that heat is absorbed by the air aroundthe reaction.D) A chemical ice pack feels cold because it isreducing the energy of the universe.
Explanations: The first law of thermodynamics states that energy cannot be created or destroyed, hoever, it can only change its state.
A) Incorrect - this is not related to thermodynamics
B) Incorrect - has no correlations to energy being conserved.
C) Correct - energy state of the heat is transfered from the system to surrounding, this is an example of thermodynamic
D) Incorrect - no energy is conserved here.
WHAT WILL BE THE PROPPER WAY FOR ANSWERING THIS QUESTION ASLIVING IN OKLAHOMA
The main way that could be told to do this is to actively show their presence in the campaign and get involved with the campaign with interest and enthusiasm.
Some other ways to tell the students of the region to do their part in a campaign are as follows:
Get involved in local campaigns and events.Write to your local representatives about the issues that matter to you.Make donations to local organizations working on the issue.Talk to your friends and family about the issue and why it's important to you.Contribute to the campaign by writing attractive slogans and making posters.Create awareness in your locality about the campaign.Arranging provisions properly for the participants taking part in the campaign.Propaganda about the campaign in social media and other modes of communication.These are some ways that could be told to the students of the region to take part in the campaign.
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Volume vs temp. Please help me find the final answer!
Given that the pressure in the whole process is constant, we could use the Charles's law:
[tex]\frac{V_1}{T_1}=\frac{V_2}{T_2}[/tex]Let's replace our values and solve the equation for T2:
[tex]\frac{623mL}{137C}=\frac{914mL}{T_2}\to T_2=\frac{137C\cdot914mL}{623mL}=201C[/tex]The temperature of the gas sample will be 201°C.
How many g of oxygen are in 4.50x1024 molecules of P205?0 43.9 gO 4.24x1022 gO 600 gO 598 g
If we have 4.50 x 10²⁴ molecules of P₂O₅, we will have 5 times as much atoms of oxygen, because in each molecule of P₂O₅ there are 5 atoms of oxygen.
So, the number of atoms of oxygenm in total, is:
[tex]5\cdot4.50\times10^{24}=22.5\times10^{24}=2.25\times10^{25}[/tex]The atomic mass of oxygen is approximately 15.9994 g/mol. So, we first need to convert the number of oxygen atoms for number of moles of oxygen.
To do that, we divide the number of atomx of oxygen by Avogadro's Numver:
[tex]N_A\approx6.022\times10^{23}mol^{-1}[/tex]So, we have:
[tex]n_O=\frac{2.25\times10^{25}}{6.022\times10^{23}mol^{-1}}=37.36300\ldots mol^{}[/tex]Now, we can convert to mass:
[tex]\begin{gathered} M_O=\frac{m_O}{n_O} \\ m_O=M_O\cdot n_O=15.9994g/mol\cdot37.36300\ldots mol=597.7856\ldots g\approx598g \end{gathered}[/tex]So, we have approximately 598 g of oxygen atom.
use the elements of the periodic table to help you identify the number of valence for each of these elements 1,2,3,4,5,6,7, or 8carbon (C) 1Chlorine (Cl) 2Neon (Ne) 3Calcium (Ca) 4Oxygen (O) 5 6 7 8
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
how much iodine (I2) in moles, should be added to water to produce 2.5L of solution with a molarity of 0.6M?
Molar concentration or Molarity is a way to measure the concentration of a solution after some solute has been added to the solvent, the formula for Molarity is:
M = n/V
where:
M = molar concentration
n = number of moles
V = volume of the solution in Liters
In the question we are given the molarity and volume, let's add these information to our formula
0.6 M = n/2.5 L
n = 1.5 moles of Iodine should be added
What does it mean if element A is higher than element B on the activity series?A.B will replace A in a single-replacement reaction.B.A will replace B in a combination reaction.C.A will replace B in a single-replacement reaction.D.B will replace A in a decomposition reaction.
Answer
C
Explanation
A higher ranked element in the activity series is more reactive in a single replacement reaction. We predict a single replacement reaction will occur when a less reactive element can be replaced by a more reactive element in a compound. Therefore since A is more reactive, it will replace B in a single replacement reaction.
The police found 488.43 grams of chlorate of
potassium (KCIO) in the room. To kill someone with the
mixture, 420.45g of potassium chloride would be required.
Is there enough potassium chloride to
that Melanie killed the butler?
KCIO3 > KCI + O2?
The formed amount of KCl from the reaction is 297.12 g which is not enough to kill someone.
What is the limiting reagent?A limiting reagent can be defined as a reactant that is exhausted completely from the mixture at the completion of a chemical reaction.
When quantities of reactant are not taken in stoichiometry, the limiting reactants in the chemical reaction will decide the maximum amount of product.
Given, a balanced equation of the decomposition of KClO₃ is:
[tex]KClO_3\longrightarrow KCl +O_2[/tex]
One mole of KClO₃ will produce one mole of KCl.
122.55 g of the KClO₃ will produce KCl = 74.55 g
Given, the amount of KClO₃ = 488.43 g
Then 488.43 g of KClO₃ will produce KCl = (74.55/122.55) × 488.43
= 297.12 grams
As given 420.45g of potassium chloride would be required to kill someone. Therefore, there is not enough potassium chloride that Melanie killed the butler.
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