Question

A)
Why are open systems inappropriate for studying the conservation of mass?
(1 point)
Matter may be lost to or gained from the surroundings.
The sample may become contaminated.
Matter may be created or destroyed within the system.
Heat can escape from or enter the system.
A)
A student claims that the reaction of hydrogen and oxygen to form hydrogen peroxide is evidencesupporting the claim that mass is conserved in a reaction. The chemical equation the student uses forthe reaction is shown:
. Does this evidence support the claim? Why or why not?
(1 point)
H2 + O2 → H2O2
Yes, it supports the claim because the equation is balanced.
Yes, it supports the claim because the mass before and after is the same.
No, it does not support the claim because more hydrogen is necessary.
No, it does not support the claim because more oxygen is necessary.

A)
A student records the masses of two reactants (baking soda & vinegar), and then mixes them. Thereactants bubble and foam, forming a paste. The student measure the mass again, and the final massis 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)
Some of the mass was left over as remnants in the containers the student used.
There was not enough of the reactants to form as much product as possible, so some reactant was leftover; this changes the final mass.
The bubbling indicates a gas was formed, so some atoms formed gas; therefore, mass was transferred tothe atmosphere.
Pastes are in between a liquid and a solid, and they have less mass than solids (i.e., baking soda).
A)
Which quantity is used to define 1 atomic mass unit (amu)?
(1 point)
One-sixteenth the mass of a neutral oxygen atom.
The mass of one neutral hydrogen atom.
One-sixteenth the mass of a neutral carbon atom.
One-twelfth the mass of a neutral carbon atom.

Use the equation to answer the question.
Which statement about the equation is correct?
(1 point)
FeC l3 + 3NH4OH → Fe(OH)3 + 3NH4Cl
Mass is conserved because the number of molecules in the reactants equals the number of molecules inthe products.
Mass is conserved because the number of different elements in the reactants equals the number ofdifferent elements in the products.
Mass is conserved because the number of each atom in the reactants equals the number of each atom inthe products.
Mass is conserved because the number of reactants equals the number of products.
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A)
The atomic mass of Iron (Fe) is 55.85 amu, and the atomic mass of chlorine (Cl) is 35.45 amu.Which molar mass is correct for iron III chloride (
)?
(1 point) FeCl3
129.59 g/mol
91.30 g/mol
126.75 g/mol
162.20 g/mol

Answer 1

1) Matter may be lost to or gained from the surroundings.

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

3) The bubbling indicates a gas was formed, so some atoms formed gas; therefore, mass was transferred to the atmosphere.

4) One-twelfth the mass of a neutral carbon atom.

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

6) 162.20 g/mol.