Conservation of Mass
This lesson covers:
- The law of conservation of mass
- Why the mass, as measured on a balance, may appear to change during a reaction
What does the law of conservation of mass state?
Atoms are made but not lost in a chemical reaction
Atoms are lost but not made in a chemical reaction
No atoms are lost or made during a chemical reaction
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What is a chemical change?
A rearrangement of the atoms in the reactants, to form the products
A change of state
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In a chemical reaction, is there any change in the overall mass of the substances?
Yes
No
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Why is it more difficult to measure the mass of a gas than the mass of a liquid or solid?
A gas doesn't have any mass
A gas has too low a mass to register on a balance
A gas can easily escape into the air
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In a chemical reaction, is there a change in the number of atoms?
Yes
No
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A chemical reaction is carried out in a beaker on a balance.
Why may the balance reading for the products be less than the reading for the reactants?
(Select all that apply)
One of the products was a gas and floated off
One of the products was a solid and precipitated
Gas from the air reacted with the reactants
Some of the reactants may have been spilled
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CaCO3 + H2SO4 ➔ CaSO4 + H2O + CO2
5g of calcium carbonate reacts completely with 4.9g of sulfuric acid to form 6.8g of calcium sulfate, 0.9g water, and some carbon dioxide gas.
What mass of carbon dioxide must have been produced during the reaction?
g
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A chemical reaction is carried out in a beaker on a balance.
Why may the balance reading for the products be more than the reading for the reactants?
One of the products was a solid and precipitated
One of the products was a gas and floated off
Gas from the air reacted with the reactants
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2Ca + O2 ➔ 2CaO
3.2g of calcium is reacted with oxygen from the air to form 4.5g of calcium oxide.
What mass of oxygen from the air must have reacted with the calcium?
g
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The law of conservation states that the mass of reactants and products is a chemical reaction will be the same.
In practice, the reading on a balance may change during a chemical reaction. Is this more likely in an open container or a sealed (closed) container?
Open container
Sealed container
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