WorksheetsChemical Reactions
Total questions: 41
Worksheet time: 27mins
A substance that is formed as the result of a chemical reaction is a __________________
Product
Reactant
Starters
Enders
Which of the following is an example of a chemical change?
water freezes to form ice
sugar dissolves in water
gasoline burns in a car engine
a piece of metal expands when it is heated
A change in the shape of an object is an example of _________________.
a chemical change
energy
an endothermic change
a physical change
Which one shows that a chemical reaction has occurred?
dissolving
melting
formation of a gas
bending
2H2 + O2 --> 2H2O
2H2 + O2 --> 2H2O
Al + O2 --> 2Al2O3
The smallest particle of an element; made of electrons, protons, and neutrons
Atoms
Elements
Molecules
Products
A solid that is deposited from a solution
Solid
Liquid
Product
Precipitate
A chemical reaction or process that absorbs heat from the surroundings
Endothermic
Exothermic
A chemical reaction or process that releases heat.
Endothermic
Exothermic
What type of reaction is this?
Exothermic
Endothermic
Energy Producing
No way to tell
In general, what happens when you increase the temperature of a reaction?
The heat destroys the reactants
The rate of the reaction decreases
The rate of the reaction increases
The rate of the reaction stays the same
Which shows a balanced chemical equation for the decomposition of aluminum oxide (Al2O3)? Hint: Which of the following is observing the Law of Conservation of Matter: Matter cannot be created or destroyed so there must be the same number of atoms on both sides of the equation.
Al2O3 → 2 Al + O2
Al2O3→ 2 Al + 3O2
2 Al2O3 → 4Al + O2
2Al2O3 → 4Al + 3O2
Which of the following reactions describes a synthesis reaction? Hint: synthesis means “to make”.
2 Na + Cl2 → 2NaCl
Mg + CuSO4 → MgSO4 + Cu
2KI → 2K + I2
CH4 +2 O2 → CO2 + 2H2O
Hydrogen and oxygen react to form water. At an atomic level, how do we know that a chemical reaction has occurred?
Hydrogen molecules are negative, and oxygen molecules are positive.
For every oxygen atom, two hydrogen atoms are needed.
The hydrogen and oxygen atoms regroup into a new molecule.
Oxygen atoms are much larger than hydrogen atoms.
Which of the following provides the best evidence that this reaction follows the law of conservation of mass?
There are the same number and type of each kind of atom on both sides of the equation.
All of the reactants that were present before the reaction are present after the reaction.
The number of molecules after the reactions changes from three molecules to two.
More chlorine and hydrogen atoms are generated during the chemical reaction.
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 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.
Is this showing an endothermic or an exothermic reaction?
Endothermic
Exothermic
