WorksheetsLaw of the Conservation of mass
Total questions: 20
Worksheet time: 10mins
Which is best represented by the equation?2Mg + O2 2MgO
Law of Conservation of Energy
Law of Conservation of Mass
Law of Superposition
How does a balanced chemical equation satisfy the Law of Conservation of Mass?
During a chemical reaction, the total amount of matter stays the same.
During a chemical reaction, matter is destroyed.
During a chemical reaction, one or more new substances are formed
During a chemical reaction, the total number of atoms increases.
If a chemical reaction such as photosynthesis begins with 8 atoms of carbon (C), how many atoms of carbon (C) should be in the products?
12
8
6
2
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 into the atmosphere.
The equation below shows a reaction between sodium (Na) and water (H2O).
2Na (s) + H2O (l) → 2NaOH (aq) + H2 (g)
Which best explains why the equation is not balanced?
There is too much sodium in the reactants.
There is not enough water in the reactants.
There is too much hydrogen gas in the products.
There is not enough sodium hydroxide in the products.
Following the lab procedures below in completing an experiment.
1. Place samples of iron filings and sulfur into a test tube.
2. Cover the test tube with a rubber sheet and seal it.
3. Measure and record the mass of the test tube and contents.
4. Heat the test tube until the contents glow red.
5. Allow the test tube to cool.
6. After cooling, remeasure and record the mass of the test tube and contents.
Which best describes the conclusion?
A change in mass occurred after heating.
No change in mass occurred after heating.
A physical change occurred, producing new products.
A chemical change occurred, producing new reactants.
Which best explains how the chemical reaction shown below follows the law of conservation of mass?
2H2 + O2 → 2H2O
The hydrogen and oxygen molecules combine to form water.
Hydrogen and oxygen are held together by strong chemical bonds.
There are hydrogen and oxygen atoms on both sides of the equation.
The same number of hydrogen and oxygen atoms are on both sides of the equation.
Max recorded the notes below as he completed an experiment in science class.
20 grams of a solute was added to 100 grams of a liquid substance. The solute completely dissolved. The total mass of the resulting solution was 120 grams after the experiment was complete.
Which best explains how the law of conservation of mass was demonstrated in the experiment?
The solute completely dissolved in the liquid.
The liquid was chemically changed by the addition of the solute.
Some of the mass of the solute was lost during the experiment.
The mass of the resulting solution was equal to the mass of the solute and liquid.
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.
Substance A has a mass of 7 grams. When substance A was mixed with substance B, a new substance was formed. Which statement best describes the Law of Conservation of Mass?
The mass of substance B is equal to the mass of the product.
The mass of the product is equal to the mass of the reactants.
The mass of the product is less than the mass of the reactants.
Which must be true if the number of atoms stays the same regardless of how they are arranged?
Their total mass must change.
Their total mass stays the same.
An open system must have been used.
Which best supports the Law of Conservation of Mass?
Atoms can be rearranged to keep the same mass.
Atoms can be destroyed to make a new substance.
Atoms can be rearranged to change their mass.
What best explains the result of substances of a chemical reaction?
A new substance is produced.
The same substance is produced.
More energy is produced in the substance
Which best describes a chemical reaction applying the law of conservation of mass?
an equation which uses energy
an equation which does not use energy
a balanced equation in which the reactants and products are equal
an unbalanced equation in which the reactants and products are unequal
Which is true of a chemical equation?
Products and reactants must be balanced.
Subscripts must be used with all products and reactants.
Energy must be included in the beginning of the reaction.
Coefficients must be used with all products and reactants.
Which best explains why conservation of mass should be studied in a closed system?
to prevent the loss of any reactants
to prevent contamination of the products
to prevent the release of any gases produced
to prevent the absorption of heat from the outside
Which is the bestsystem to use when studying the law of conservation of mass?
a closed system to measure the mass of the reaction
an open system to measure the mass of the reaction
a large system to give the reaction space to occur
a small system to closely observe the reaction
Two substances react and the mass is recorded. The mass of the products does not equal the mass of the reactants. Which is thebest explanation for the difference in the masses?
The scale was not balanced.
Some of the mixture spilled.
Gas was produced and lost to the environment.
Substances were added after the initial mass was recorded.
A experiment was conducted to test the law of conservation of mass. At the end of the experiment, only 82% of the mass of the initial reactants was present. The experiment was repeated three times with similar results. Which best explains why some of the mass was lost?
The mass escaped as a gas.
The mass transformed into a liquid.
The mass remained part of the reactant.
The mass turned into a heavier chemical.
Sodium sulfate and barium chloride react with each other to form sodium chloride and barium sulfate as shown.
Which statement MOST accurately describes the mass of the reactants compared to the mass of the products?
The mass of the reactants is the same as the mass of the products.
The products have a greater mass because matter was created during the reaction.
The reactants have a greater mass because some of the mass was converted to heat.
The reactants have a greater mass because some matter was destroyed by the reaction.
