20 questions
Law of conservation of mass states that
mass is created
mass is destroyed
mass is neither created nor destroyed
mass does not change
100g of white powder reacts with 77g of clear liquid. The reaction bubbles and changes color producing a yellow liquid that has a mass of 90g. What can be concluded?
97g of gas was produced
This experiment violates the conservation of mass
87g of gas was produced
The excess reactant is destroyed & disappears during the reaction
Suppose a reaction were to happen in an open container in a lab. During the reaction, the scientist observes the chemicals bubble, and produce a gas. During the analysis the scientist notices that the reactants weighed 20 g when he started, and the product weighed 18 g. Explain what happened.
His chemical reaction defied the law of conservation of mass
The product destroyed mass during the reaction
The reactants created matter during the reaction
The gas that was produced was not able to be weighed since the container was open.
Mass cannot be created or__________ during a chemical reaction?
Reacted
Transferred
Born
Destroyed
Which compounds are the PRODUCTS of this reaction?
CO2 + H2O
C6H12O6 + O2
C6H12O6 + CO2
H2O + O2
What coefficient for O2 demonstrates the law of conservation of mass?
CH4(g) + __O2 → CO2 + 2H2O
1
2
3
4
How does the concept of conservation of mass apply to chemical reactions?
The reactants and products have exactly the same atoms.
The reactants and products have exactly the same molecules.
The change in the amount of matter is equal to the change in energy.
The change in the amount of matter is only a small percentage of the total mass
A chemical reaction separates water into hydrogen gas and oxygen gas. Which of the following statements is true about the mass of the water and the combined mass of the two gases?
The mass of the water is greater than the combined mass of the two gases.
The combined mass of the two gases is much greater than the mass of the water
The combined mass of the two gases is the same as the mass of the water.
The mass of the water is the same as double the combined mass of the two gases
If a chemical reaction such as photosynthesis begins with 6 atoms of carbon (C), how many atoms of carbon (C) should be in the products?
12 atoms of carbon (C)
6 atoms of carbon (C)
3 atoms of carbon (C)
2 atoms of carbon (C)
Which best explains why the total mass of the product(s) would be less than the total weight of the reactant(s) after a chemical reaction?
A physical change occurred
Atoms involved in the reaction lost mass
Precipitates were created in the new solution
Gases were released to the atmosphere
When chemicals react in a closed container, which must be true?
The mass both before and after the reaction is the same
The mass both before and after the reaction is variable
The same number of compounds is present both before and after the reaction
Which best represents a balanced equation?
120 grams of carbon plus 20 grams of oxygen → 200 grams of carbon dioxide
120 grams of carbon plus 50 grams of oxygen → 200 grams of carbon dioxide
120 grams of carbon plus 80 grams of oxygen → 200 grams of carbon dioxide
What is the importance of a closed container in a chemical reaction?
to observe the mass before and after the reaction occurs
to keep any materials from interfering with the reaction
to observe the loss of mass after the reaction occurs
If 100 grams of vinegar and 5 grams of baking soda are poured in a container, a small amount of gas will be produced. What will the final mass of the products be if the gas is trapped in the container?
100 grams
104 grams
105 grams
110 grams