WorksheetsChemical Reactions Unit
Total questions: 24
Worksheet time: 12mins
A substance that enters into a chemical reaction is called a
mole.
product.
coefficient.
reactant.
In a reaction in which hydrogen reacts with oxygen to produce water, which substances are the reactants?
hydrogen only
oxygen only
both hydrogen and oxygen
water
Which of the following is not an example of a chemical change?
rusting iron
an apple ripening
cutting paper
a piece of wood burning
In a chemical reaction, what is the relationship between the total mass of the reactants and the total mass of the products?
They must be equal.
The mass of the products must be greater.
The mass of the reactants must be greater.
There is no general relationship between the two.
What is the general form for a single-replacement reaction?
AX + BY --> AY + BX
AB --> A + B
A + B --> AB
A + BX --> AX + B
What is the general form for a double-replacement reaction?
AX + BY --> AY + BX
AB --> A + B
A + B --> AB
A + BX --> AX + B
What kind of reaction is represented by the equation C2Cl4 + Cl2 --> C2Cl6?
synthesis
double replacement
single replacement
combustion
According to the law of conservation of mass, the total mass of the reacting substances is
always more than the total mass of the products.
always less than the total mass of the products.
sometimes more and sometimes less than the total mass of the products.
always equal to the total mass of the products.
The reaction 2Mg + O2 --> 2MgO is a
synthesis reaction.
decomposition reaction.
single-replacement reaction.
double-replacement reaction.
The reaction Mg + 2HCl --> H2 + MgCl2 is a
composition reaction.
decomposition reaction.
single-replacement reaction.
double-replacement reaction.
The reaction 2HgO --> 2Hg + O2 is a(n)
single-replacement reaction.
synthesis reaction.
ionic reaction.
decomposition reaction.
The reaction Pb(NO3)2 + 2KI --> PbI2 + 2KNO3 is a
double-replacement reaction.
synthesis reaction.
decomposition reaction.
combustion reaction.
The reaction 2KClO3 --> 2KCl + 3O2 is a(n)
synthesis reaction.
decomposition reaction.
combustion reaction.
ionic reaction.
What makes a chemical reaction EXOTHERMIC?
heat is absorbed
heat is released
atoms are lost
atoms are destroyed
What makes a chemical reaction ENDOTHERMIC?
heat is RELEASED
heat is ABSORBED
atoms are created
atoms are destroyed
A student is using the following key to model the chemical equation below.
Chemical Equation:
MgCl2 + 2NaF → MgF2 + 2NaCl
The reactants are on the left and the products are on the right. How many blue beads will the student need to model each side of the equation?
1 for the products and 1 for the reactants
2 for the products and 2 for the reactants
2 for the products and 1 for the reactants
1 for the products and 2 for the reactants
Students want to gather evidence for the claim that the number of atoms present before a chemical reaction is equal to the number of atoms present after the chemical reaction. They decide to react vinegar and baking soda in a sealed plastic bag. Which of the following would provide the evidence the students need?
The mass of the plastic bag, baking soda and vinegar before the reaction was equal to the mass after the reaction.
Bubbles were produced during the reaction which meant that a gas was being produced.
The plastic bag did not change in any way, indicating that it was not involved in the reaction.
The mass of the baking soda was exactly equal to the mass of the vinegar used to create the chemical reaction.
Which of the following is true regarding the atoms involved in a chemical reaction?
The same number of each type of atom will always be present before and after a chemical reaction takes place
Some of the atoms present before the reaction will always be lost during a chemical reaction
Some of the atoms will always be changed into a different type of atom by a chemical reaction.
During a chemical reaction, atoms will always be combined into much larger molecules.
In a chemical reaction known as decomposition, carbonic acid breaks down into water, and what other compound?
Which of the following atomic models of chemical reactions correctly demonstrates the Law of Conservation of Matter?
Students were learning about chemical reactions. They learned that there are reactions in which one molecule breaks down into other molecules or atoms, and many of these reactions have useful applications. For example, a chemical called sodium azide (NaN3) can break down into sodium metal (Na) and nitrogen gas (N2) inside air bags in cars. The nitrogen gas is what fills the air bag.
As another example, water molecules (H2O) can break down to form oxygen gas (O2) and hydrogen gas (H2). The students wondered how much oxygen gas and hydrogen gas are produced when water breaks down. They wanted to find out if they could predict the amounts based on a model of the reaction. They used the information they had learned to develop a model, as shown.
What does the students’ model show about the relationship between the numbers of atoms present before and after the reaction?
The number of oxygen atoms before the reaction is greater than the number of oxygen atoms after the reaction.
The number of hydrogen atoms before the reaction is greater than the number of hydrogen atoms after the reaction.
The total number of hydrogen and oxygen atoms before the reaction is equal to the total number of hydrogen and oxygen atoms after the reaction.
The total number of hydrogen and oxygen atoms before the reaction is less than the total number of the hydrogen and oxygen atoms after the reaction.
A group of students have developed a model to illustrate the Law of Conservation of Matter. The students’ teacher asks them to use their model to make a prediction. The students need to predict the total mass of hydrogen gas and oxygen gas produced when 2 grams of water break down.
Based on the students’ model, what is the best prediction for the total mass of the products of this reaction?
2 grams
3 grams
5 grams
6 grams
Choose the two balanced equations from below:
C5H8O2 +2NaH+2HCl → C5H12O2 +2NaCl
4H2SiCl2 + 4H2O → H8Si4O4 + 6HCl
C4H10O+ 6O2 → 6CO2 + 5H2O
4Fe+ 3O2 → 2Fe2O3
Using your understanding of the Law of Conservation of Matter, select the following statements that are true when balancing a chemical equation.
Matter cannot be created or destroyed.
Subscripts cannot be added, removed, or changed.
Coefficients can go both in front of and in the middle of chemical formulas.
You can only change coefficients.
