Why are open systems inappropriate for studying the conservation of mass?(1 point)

Question

Responses

Matter could be created or destroyed within the system.
Matter could be created or destroyed within the system.

The sample could become contaminated.
The sample could become contaminated.

Matter could be lost or gained from the surroundings.
Matter could be lost or gained from the surroundings.

Heat could escape from or enter the system.
Heat could escape from or enter the system.
Question 2
A student claims that the reaction of hydrogen (H2
) and oxygen (O2
) to form hydrogen peroxide is evidence supporting the claim that mass is conserved in a reaction. The chemical equation the student uses for the reaction is shown:

H2
+ O2
→
H2O2

Does this evidence support the claim? Why or why not?

(1 point)
Responses

Yes, it supports the claim because the equation is balanced.
Yes, it supports the claim because the equation is balanced.

Yes, it supports the claim because the mass of the products is greater than the mass of the reactants.
Yes, it supports the claim because the mass of the products is greater than the mass of the reactants.

No, it does not support the student's claim because more oxygen is necessary.
No, it does not support the student's claim because more oxygen is necessary.

No, it does not support the student's claim because more hydrogen is necessary.
No, it does not support the student's claim because more hydrogen is necessary.
Question 3
A student records the masses of two reactants (baking soda and vinegar), and then mixes them. The reactants bubble and foam, forming a paste. The student measures the mass again, and the final mass is slightly less than the sum of the initial masses. Considering that mass is supposed to be conserved, which statement is a possible explanation for this "loss" of mass?(1 point)
Responses

Some of the mass was left over as remnants in the containers the student used.
Some of the mass was left over as remnants in the containers the student used.

Pastes are in between a liquid and a solid, and they have less mass than solids like baking soda.
Pastes are in between a liquid and a solid, and they have less mass than solids like baking soda.

The bubbling indicates that a gas was formed, so some atoms formed gas. Therefore, mass was transferred to the atmosphere.
The bubbling indicates that a gas was formed, so some atoms formed gas. Therefore, mass was transferred to the atmosphere.

There was not enough of one of the reactants to form as much product as possible, so some reactant was left over. This changes the final mass.
There was not enough of one of the reactants to form as much product as possible, so some reactant was left over. This changes the final mass.
Question 4
Which quantity is used to define 1 atomic mass unit?(1 point)
Responses

one-sixteenth the mass of a neutral oxygen atom
one-sixteenth the mass of a neutral oxygen atom

one-twelfth the mass of a neutral carbon atom
one-twelfth the mass of a neutral carbon atom

one-sixteenth the mass of a neutral carbon atom
one-sixteenth the mass of a neutral carbon atom

the mass of one neutral carbon atom
the mass of one neutral carbon atom
Question 5
[This is the stem.](1 point)
Responses

Mass is conserved because the number of different elements in the reactants equals the number of different elements in the products.
Mass is conserved because the number of different elements in the reactants equals the number of different elements in the products.

Mass is conserved because the number of reactants equals the number of products.
Mass is conserved because the number of reactants equals the number of products.

Mass is conserved because the number of each atom in the reactants equals the number of each atom in the products.
Mass is conserved because the number of each atom in the reactants equals the number of each atom in the products.

Mass is conserved because the number of molecules in the reactants equals the number of molecules in the products.
Mass is conserved because the number of molecules in the reactants equals the number of molecules in the products.
Question 6
The atomic mass of nickel (Ni
) is 58.693 amu, and the atomic mass of chlorine (Cl
) is 35.45 amu. Which molar mass is correct for nickel chloride (NiCl2
)?(1 point)
Responses

152.84 g/mol
152.84 g/mol

129.59 g/mol
129.59 g/mol

94.14 g/mol
94.14 g/mol

188.29 g/mol
188.29 g/mol
Question 7
When the products of a reaction are known, which fact can always be deduced about the reactants?(1 point)
Responses

the number of reactants
the number of reactants

the state of the reactants
the state of the reactants

the mass of each reactant
the mass of each reactant

the number of atoms in the reactants
the number of atoms in the reactants
Question 8
(1 point)
Responses

Fe2O3
cap f e sub 2 cap o sub 3

2Fe2O3
2 cap f e sub 2 cap o sub 3

4FeO2
4 cap f e cap o sub 2

3FeO2
3 cap f e cap o sub 2
Question 9
Calcium carbonate (CaCO3
) can undergo a chemical reaction to produce calcium oxide (CaO
)and carbon dioxide. Which possible masses of calcium oxide and carbon dioxide (CO2
) can form when 200g of calcium carbonate undergoes this chemical reaction?(1 point)
Responses

200g CaO
and 200g of CO2
200g cap c A cap o and 200g of cap c cap o sub 2

40g CaO
and 12g of CO2
40g cap c A cap o and 12g of cap c cap o sub 2

112g CaO
and 88g of CO2
112g cap c A cap o and 88g of cap c cap o sub 2

56g CaO
and 44g of CO2
56g cap c A cap o and 44g of cap c cap o sub 2
Question 10
(1 point)
Responses

274g
274g

130g
130g

144g
144g

270g
270g
Question 11
(1 point)
Responses

For every 4 moles of water produced, 3 moles of propane react.
For every 4 moles of water produced, 3 moles of propane react.

For each mole of oxygen that reacts, 3 moles of carbon dioxide are produced.
For each mole of oxygen that reacts, 3 moles of carbon dioxide are produced.

For each mole of propane that reacts, 5 moles of oxygen are produced.
For each mole of propane that reacts, 5 moles of oxygen are produced.

For every 3 moles of carbon dioxide produced, 5 moles of oxygen react.
For every 3 moles of carbon dioxide produced, 5 moles of oxygen react.
Question 12
(1 point)
Responses

24
24

96
96

48
48

16
16
Question 13
The molar mass of BF3
is 67.81 g/mol. How many molecules of BF3
are there in 2.0g?(1 point)
Responses

4.084 x 1025
4.084 x 10 to the 25th power

8.881 x 1021
8.881 x 10 to the 21th power

1.776 x 1022
1.776 x 10 to the 22th power

1.204 x 1024
1.204 x 10 to the 24th power
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Answer 1

Here are the recommended answers for each question:

Question 1:

Why are open systems inappropriate for studying the conservation of mass?

• Response: Matter could be lost or gained from the surroundings.

Question 2:

Does the reaction of hydrogen (H2) and oxygen (O2) to form hydrogen peroxide support the claim that mass is conserved?

• Response: No, it does not support the student's claim because more oxygen is necessary.

Question 3:

What might explain the "loss" of mass in the reaction between baking soda and vinegar?

• Response: The bubbling indicates that a gas was formed, so some atoms formed gas. Therefore, mass was transferred to the atmosphere.

Question 4:

Which quantity is used to define 1 atomic mass unit?

• Response: one-twelfth the mass of a neutral carbon atom.

Question 5:

Why is mass conserved in chemical reactions?

• Response: Mass is conserved because the number of each atom in the reactants equals the number of each atom in the products.

Question 6:

What is the correct molar mass for nickel chloride (NiCl2)?

• Response: 152.84 g/mol.

Question 7:

When the products of a reaction are known, what can always be deduced about the reactants?

• Response: the number of atoms in the reactants.

Question 8:

(Chemical formula question; the correct formula for iron(III) oxide)

• Response: Fe2O3.

Question 9:

Which possible masses of calcium oxide and carbon dioxide can form from 200g of calcium carbonate (CaCO3)?

• Response: 112g CaO and 88g of CO2.

Question 10:

(Mass-related question; please clarify if more information is needed)

Question 11:

(Chemical reaction stoichiometry question; please clarify if more information is needed)

Question 12:

(Chemistry concept; please clarify if more information is needed)

Question 13:

How many molecules of BF3 are there in 2.0g?

• Response: 1.776 x 10^22.

If you have specific questions about Questions 10, 11, or 12, please provide additional context for accurate answers.