When a scientist performs an experiment, there are many changes that can occur. Which observation should she list as a chemical change?.

Answers

Answer 1

The substance must change into a new substance is the observation that scientist must list for a chemical reaction to happen.

A chemical reaction is a procedure that causes one group of chemical components to change chemically into another. Chemical reactions, which can frequently be described by a chemical equation, traditionally include changes that only affect the locations of electrons in the formation and dissolution of chemical bonds between atoms, with no change to the nuclei (no change to the elements present). The study of chemical processes involving unstable and radioactive elements, where both electronic and nuclear changes may take place, is known as nuclear chemistry.

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Related Questions

Decompositionof ammonium nitrate produces water and di nitrogen oxide. a) Predict how many grams of water will be produced from decomposition of 0.555 kg of ammonium nitrate.b) If 120. g of water is actually produced, what is the percent yield for this reaction

Answers

NH4NO3(s) ==> 2 H2O(g) + N2O (g) (balanced)

a) We need the molar masses for each compound:

NH4NO3 = 80.0 g/mol (ammonium nitrate)

H2O = 18 g/mol (water)

0.555 kg => 1 kg = 1000 g => 0.555 kg = 555 g

80.0 g NH4NO3 -------- 2 x 18 g H2O

555 g NH4NO3 -------- X = 250 g

Answer a): 250 g water

b) % yield of water

120. g of water = actual yield

250 g of water from a) is the theoretical yield

Therefore, the % yield:

% yield = (actual yield/ theoretical yield) x 100

% yield = 120. g water/250 g water x 100

% yield = 48 %

Answer b): % yield = 48 %

THIS IS I NEED HELP FAST

Answers

Answer: Quadrant 1: (1/3, 2 1/3)

Quadrant 2: (-1 1/3, 3 1/3)

Quadrant 3: (-3, -10), (-3 1/3, -1 1/3)

Quadrant 4: (9, -1), (1 1/3, -1 1/3)

Explanation:

Graph these coordinates on an XY plane to visualize which quadrant they land in.

Look at the data in Figure 1. Fresh water has a salinity close to 0%. What is the surface tension for fresh water?

Answers

Answer: It appears as though fresh water has a surface tension of 72.5 mN/m

Explanation: Since fresh water does not have a high concentration of salt, and pure fresh water has no salt at all, you are trying to find the value of surface tension at 0% salinity. At 0% salinity, the surface tension value is 72.5 mN/m

an amino acid that forms a solution with a ph of 3.0 as it is dissolved in distilled water has a side chain with what functional group?

Answers

An amino acid that forms a solution with a ph of 3.0 as it is dissolved in distilled water has a side chain with a carboxyl group.

A carbonyl and hydroxyl group are joined by a carbon atom to form a carboxyl group. The hydroxyl group is made up of oxygen and hydrogen bound together, whereas the carbonyl group is a carbon double-bonded to oxygen (O=H) (OH). The carboxyl functional group, also known as the carboxyl group, is produced when the carbon atom is attached to both the hydroxyl and carbonyl functional groups.

This characteristic enables this functional group to bind to a variety of molecules that are present in typical goods. As a result, a molecule made up of a carbonyl and a hydroxyl group joined by a carbon atom is described as having a carboxyl group.

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The bond formed between two nonmetals, which are usually very similar in their tendency to lose or gain electrons, is the _____ bond. This bond involves the _____ of one or more electron pairs between the two atoms.

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The bond formed between two nonmetals, which are usually very similar in their tendency to lose or gain electrons, is the covalent bond. This bond involves the sharing of one or more electron pairs between the two atoms.

What is covalent bond?

A covalent bond is produced by the equal sharing of electrons from both participating atoms. This sort of bonding involves a shared pair or bonding pair of electrons. The sharing of bonding pairs will ensure that the atoms reach stability in their outer shell, analogous to the atoms of noble gases.

Elements with very high ionisation energies are incapable of transmitting electrons, while elements with very low electron affinity are incapable of absorbing electrons.

Atoms of such elements tend to share electrons with atoms of other elements or atoms of the same element in such a way that both atoms achieve octet configuration in their respective valence shells and thus achieve stability. Covalent Bond refers to such a link formed by the sharing of electron pairs among distinct or similar kinds.

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when a piece of wood is on fire how is that fired created through a chemical reaction ?

Answers

It created through chemical reaction because it feeds the fire and the oxygen does too.

which metalloid has five valence electrons in the fourth electron shell​

Answers

Answer:

Explanation:

Arsenic is the the metalloid which has "five valence electrons" in the "fourth electron shell". Explanation: Metalloids are found between the metals and non-metals in the periodic table.


hope it helps

What does a scientist mean when he or she says an object is at rest?(1 point) Responses The object is not speeding up or slowing down. The object is not speeding up or slowing down.
The object has no forces acting on it.
The object has no forces acting
on it. The object has no attractive forces acting on it. The object has no attractive forces acting on it. The object is not moving relative to its surroundings.

Answers

Scientist mean when he or she says an object is at rest then the object is not moving relative to its surroundings

Velocity of the object is said to be uniform when its speed and direction does not change and the object at rest has uniform speed of zero all the time and does not even change the direction and when object is at rest position then the velocity is zero such an object will not change its state of motion that's why when he or she says an object is at rest the scientist says that the object is not moving relative to its surroundings

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Is a salt obtained as a reaction between a base and an acid?

Answers

To answer if a salt is formed between the reaction of a base and an acid, we need to remember that, if we react a strong acid and a strong base, such as HCl and NaOH, two products will be formed: the appropriate salt and water.

In the example above, we can write the reaction as:

HCl + NaOH -> NaCl + H2O

where a strong acid and a strong base react to form a salt (NaCl) and water (H2O).

Thus, we can say that, yes, a salt is formed when an acid and a base react between each other.

What is the electron configuration of Silicon in Ground state ?

A) 1s22s22p63s23p14s1

B) 1s22s22p63s4

C) 1s22s22p63s23p2

D) 1s22s22p63s23p3

Answers

C,
Si is in the 3p orbital which occupies 2 electrons

Chemical equations Help pleaseeeeee

Answers

4555The number is the number that you

Why do isotopes undergo radioactive decay?

Answers

Isotopes undergo radioactive decay because thermodynamics generally governs the situation. Every atom strives to have the greatest degree of stability. When the number of protons and neutrons in the atomic nucleus is out of balance, instability results in radioactive decay. In essence, the nucleus contains too much energy to keep all the nucleons together.

Radioactive decay a the spontaneous process through which an unstable atomic nucleus breaks into smaller, more stable fragments.

Three Types of Radioactive Decay:

Alpha Decay:

       When an alpha particle basically a helium nucleus with two protons and two neutrons is ejected, the parent's atomic number and mass number are reduced by two and four, respectively.

Beta Decay:

      A stream of electrons from the parent, known as beta particles, is released during beta decay, and a neutron in the nucleus is changed into a proton. The new nucleus has the same mass number, but an additional atomic number of one.

Gamma Decay:

        The atomic nucleus releases extra energy during gamma decay in the form of high-energy photons (electromagnetic radiation). The resultant nucleus takes on a more stable energy state while maintaining the same atomic number and mass number.

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3) According to internet sources
the Moon has an equatorial
VectorStock
radius of 1738.14 km and a polar radius of 1735.97 km.
What information can you tell me about these
measurements just by looking at the numbers? How many
miles do these numbers represent? Is the moon a perfect
sphere? How confident are you in your answer?
Vector. PLEASE HELP MEE

Answers

According to internet sources the Moon has an equatorial VectorStock radius of 1738.14 km and a polar radius of 1735.97 km and the miles do these numbers represent 2.17km and yes moon a perfect sphere

Miles is a unit of distance equal to 1760 yards or approximately 1.6 kilometers

Here given data is

Moon has an equatorial VectorStock radius of 1738.14 km and a polar radius of 1735.97 km then the miles are

1738.14 km - 1735.97 km = 2.17km

2.17 km miles do these numbers represent? Is the moon a perfect sphere

And the moon is the perfect sphere

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• What happens to matter during chemical reactions Are the atoms the same or different before and after the reaction?​

Answers

Answer:

only the atoms present in the reactants can end up in the products.

Explanation:

Jillian is looking over a Safety Data Sheet (SDS) for a pesticide at work. She notices it has the exclamation point pictogram shown below. What does this pictogram mean?

A red diamond with an exclamation mark inside

Chemicals that could cause toxicity to fish and other aquatic life
Chronic hazard that comes from long-term exposure
Health hazard that is less severe
Toxic poisoning after brief exposure

Answers

Answer:

This symbol indicates that hazardous products with this pictogram can cause certain health effects for example, skin irritation, eye irritation, and/or. skin sensitization.

Explanation:

Which of these groups would be MOST concerned with technological developments in insect control?

A.
archaeologists

B.
paleontologists

C.
meteorologists

D.
agriculturists

Answers

Answer:

archaeologists

Explanation:

Meteorologist: weather man

Paleontologist: a scientist who studies the history of life on Earth through the fossil record.

Agriculturalist: One who practices agriculture, a farmer, a gardener.

archaeologists: Archaeologists can work for research organizations, consulting and cultural resource management firms, government agencies, and museums.

Energy and Temperature Activity Worksheet

Instructions: Follow the directions below to complete part one and part two of this activity. You will submit both parts once completed.

Note: You are not performing the experiment—only designing it.

Shape

Introduction

The purpose of this assignment is to design an experiment that another student could follow and use to test whether land or water heats faster.

You will complete the following:

Part One: Experimental Design. Plan out an experiment by answering the guiding questions below.

Part Two: Design a Lab Report. Write the outline of a lab report so that another student could complete the experiment by using the materials listed below:

sand

water

heat lamps

thermometers

cups

Shape



Part One: Experimental Design

Use these guiding questions to create the experiment. Answer each question below:

What hypothesis will the experiment test?

What are the variables?

What purpose would the sand serve?

What purpose would the water serve?

What purpose would the heat lamps serve?

What purpose would the thermometers use?

How can you use these materials to test whether land or water heats faster?

How would you compare whether land or water heats faster?

Within a 24-hour period, at what three points should the temperature be taken? Why?

What would an effective conclusion need to include?

can someone help me with part one please ☆ ~('▽^人) you'll receive 100 points

Answers

Land surfaces are much darker so they absorb much more solar radiation than water. Most of the solar radiation is reflected by water which leads in reflecting the solar radiation that reaches the surface back in to the atmosphere.

How does this occur?

Due to lower specific heat of sand it heats up faster than water. On the other hand water requires one calorie of energy to raise the temperature of one gram of water by one degree Celsius. Sand takes 19 calories per gram to raise the temperature of the sand by 1 degree Celsius.  While Sand requires fewer calories to raise its temperature one degree Celsius and that’s why it heats up faster than water.

Land absorbs more solar radiation the land surface retains more heat as do the vegetation for energy.

Therefore, during this experiment the sand heats up much faster than water. This happens because of the specific heat of the sand that initiates the heating rapidly under the lamp as the time passes.

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1.40 L solution was made by mixing 69.3 mL of dioxane, Which has a density of 1.03 g/mL, and 1.3 L of Toluene, Which has a density of 0.87 g/mL. Calculate the volume percent of dioxane in the solution. Be sure your answer has the right number of significant digits.? %(v/v)

Answers

To calculate the volume percent of dioxane we will apply the following formula:

[tex]Volumepercent=\frac{\text{Volume of solute}}{Volume\text{ of solution}}\times100[/tex]

In this case, the solute will be dioxane, and the volume will be 69.3 mL.

To calculate the volume of solution we will sum both volumes:

Volume of solution = Volume of dioxane + Volume of Toluene

Volume of solution = 69.3 mL + 1300 mL

Volume of solution = 1369.3 mL

[tex]Volumepercent=\frac{\text{6}9.3\text{ mL}}{1369.3\text{ mL}}\times100\text{ = 5.1}[/tex]

We are given all the data with a significant digit, therefore we must report the result also with a significant digit. So the answer will be.

The volume percent of dioxane in the solution is 5.1 %(v/v)

how many grams of chloroethane are needed to produce 5 moles of ethylamine from ammonia if the reaction yield is 67%?​

Answers

Answer:

This reaction is reversible, and you will only get significant amounts of the free amine if you use a large excess of ammonia. The product as a nucleophile.

Explanation:

classify the following as a heterogeneous mixture (suspension), homogeneous mixture (solution), or colloid: hot tea with lemon

Answers

Hot tea with lemon is classified as a homogeneous mixture as once the two components are mixed they maintain uniform composition through out the mixture.

The mixtures can be classified broadly into 3 types:

(on the basis of composition)

homogeneous

heterogeneous

colloids

Homogenous mixtures are those mixtures in which the composition of the mixture is uniform throughout the mixture.

Hetrogenous mixtures reffer to those mixtures where the composition of does not remain uniform through out the mixtures. These can consists two or more compounds in differet phases.

A colloid is a mixture of particles that are too big when compared to the atom but still are invisible to the direct eye. The particles present in a colloidal mixture range from 1 to 1000 nanometers in diameter

Hot tea with lemon is classified as a homogeneous mixture as once the two components are mixed they maintain uniform composition throughout the mixture.

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PLEAE HELP SCIECE I WILL GIVE YOU BRAINLIEST

Answers

Answer:

You have to record it before

I onlyI and II onlyII onlyII and III onlyI and III onlyIII only

Answers

The species that act as acid are the ones that donates H⁺ in the reaction.

Since we are working with an equilibrium, we have to consider both directions.

From left to right, we have H₂O turning into OH⁻ because it lost one H⁺, so H₂O is acting as an acid in the forward reaction.

From right to left, we have CH₃NH₃⁺ tunrning into CH₃NH₂ because it lost one H⁺, so CH₃NH₃⁺ is acting as an acid in the backwards reaction.

So, the species that act as acids are H₂O and CH₃NH₃⁺, I and II only.

If 7.34 mol of O2 reacts, calculate the grams of CO2 produced.CH4 + 2O2—> CO2 + 2H2O

Answers

Answer:

[tex]161.48\text{ g}[/tex]

Explanation:

Here, we want to get the mass of carbon (iv) oxide produced

From the question, we have the balanced chemical reaction stating that 2 moles of oxygen molecule produced 1 mole of carbon (iv) oxide molecule

The number of moles of carbon (iv) oxide produced from 7.34 mol oxygen is thus:

[tex]\frac{7.34\times1}{2}\text{ = 3.67 moles}[/tex]

1 mole of carbon (iv) oxide contains 44 g

The mass in 3.67 moles will be:

[tex]44\times3.67\text{= 161.48 g}[/tex]

Which of the following is an empirical formula?A.) P4O10B.) C2H4C.) H2O2D.) N2O

Answers

Answer:

N2O is an empirical formula

Explanation:

A.) P4O10   NO:  Can be reduced to P2O5

B.) C2H4    NO:  Can be reduced to CH2

C.) H2O2     NO:  Can be reduced to H O

D.) N2O     YES, the formula cannot be reduced any further.

Given the following unbalanced equation: KClO3 -> KCl + O2A) how many molecules of O2 can be produced by letting 12.00 moles of KClO3 react?B) how many moles of KCl can be produced by letting 4 moles of KClO3 react?

Answers

Step 1: Balance the equation

To balance the equation it is necessary to have the same number of atoms of each element on both sides of the equation (reactant side and product side). Let's count the number of atoms of each element for the unbalanced equation: KClO3 -> KCl + O2

Reactant side:

K - 1

Cl - 1

O - 3

Product side:

K - 1

Cl - 1

O - 2

To balance the equation, we need to fix the number of atoms of O on the product side, let's add a 3/2 in front of it:

KClO3 -> KCl + 3/2 O2

The equation is balanced but 3/2 is not an integer. So let's multply all the equation by 2:

2 KClO3 -> 2 KCl + 3 O2

Now the equation is balanced.

A) To solve this, we need to use the ratio between O2 and KClO3. It is 3:2.

so:

3 moles of O2 ---- 2 moles of KClO3

x moles of O2 ---- 12 moles of KClO3

x = 18 moles of O2

We found the number of moles, the question asks us the number of molecules.

For this, we need to use the avogadro's constant:

6.022x10^23 molecules ---- 1 mol

x molecules ---- 18 moles

x = 1.1 x 10^25 molecules of O2

B) To solve this we use the ratio between KCl and KCl3. It is 2:2

So it is produced 4 moles of KCl when 4 moles of KClO3 react.

When the ph of a solution decreases from 4. 0 to 2. 0, how does the concentration of h3o+ change?.

Answers

Hydronium ion concentration increases by 100 fold on decreasing the pH of solution from 4 to 2.

In order to compute pH, the log of the hydronium ion concentration was used.

pH = -log [Hydronium ion concentration]

So, at pH 2.0 number of hydronium ions are 10^-2

And at pH 4.0 number of hydronium ions are 10^-4

By decreasing pH there will be 100 times more hydronium ions.

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where are the reproductive parts of plants located?leaves,flower,roots, stem

Answers

The reproductive part of plants is located in flowers.

The flowers are the reproductive part of a plant.

Stamens are the male reproductive part.

The pistil is the female reproductive part.

Process of reproduction in a plant:

Pollen is transferred from one flower to another by insects or the wind. Pollination is the name given to this procedure.When pollen enters a fresh flower, it moves to the ovary where it fuses the ovules, the egg cells that become seeds, to produce seeds.Animals or the wind can disperse the seeds.

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PLEASE HELP 50 POINTS. PLEASE !!! BALANCING CHEMICAL EQUATIONS

Answers

Answer: 1st one is 1 N2 + 3 H2 > 2 NH3

               2nd one is 2 KCLO3 > 2 KCL+3 O2

              3rd one is 2 NaCL + 1 F2 > 2 NaF+CL2

> are the arrows

The numbers in front of the other numbers are the coefficient.

The numbers behind the numbers are the exponents.

C6H12O6 + 6 O2(g) 6 CO2(g) + 6 H2O(g)
If 7.5 g of glucose react with 5.5 L of oxygen, which one is the limiting reagent?

Answers

C₆H₁₂O₆   +    6O₂    --->   6CO₂   +   6H₂O, If 7.5 g of glucose react with 5.5 L of oxygen,  the limiting reagent is glucose.

The balanced reaction is given as :

C₆H₁₂O₆   +    6O₂    --->   6CO₂   +   6H₂O

mass of glucose = 7.5 g

molar mass of glucose = 180 g/mol

number of moles =mass / molar mass

                            = 7.5 / 180

                            = 0.041 mol

volume of oxygen = 5.5 L

density of oxygen = 1.42 g/ml

mass = density × volume

mass = 1.42 × 5.5

mass = 7.81

moles = mass / molar mass

           = 7.81 / 32

           = 0.244 mol

mass of reactant from each product:

now, glucose ,  mass of CO₂ = 0.041 × 6 × 44 = 10.84 g

oxygen, mass of CO₂ = 0.244  × 6 × 44  = 64.41 g

Since glucose gives the smaller amount of product glucose is a limiting reagent.

Thus, C₆H₁₂O₆   +    6O₂    --->   6CO₂   +   6H₂O, If 7.5 g of glucose react with 5.5 L of oxygen,  the limiting reagent is glucose.

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Help pls I have 5 min pls

Answers

Yes the answer ur on is the right answer
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