WorksheetsChemical Reactions Test
Total questions: 10
Worksheet time: 3hrs 30mins
A chemical change is different than a physical change because in a chemical change
Chemicals are used
Molecules do not physically touch
A new substance is formed and in a physical change no new substance is formed.
The change can be seen but in a physical change it cannot
In a chemical reaction
The atoms of the reactants always stay together to form the products.
The atoms of the reactants un-bond, rearrange, and then re-bond to form the products.
New atoms are formed which combine to make the products
Some atoms disappear while others multiply to form the products
In the chemical reaction CH4 + 2O2 --> CO2 + 2H2O, there are reactants on the left of the equation and products on the right. If you count the atoms in the reactants, there are
4 carbon atoms, 4 hydrogen atoms, and 2 oxygen atoms
1 carbon atom, 4 hydrogen atoms, and 2 oxygen atoms
1 carbon atom, 4 hydrogen atoms, and 4 oxygen atoms
4 carbon atoms, 4 hydrogen atoms, and 4 oxygen atoms
In a chemical reaction, mass is conserved. This means that
The mass of the reactants stays the same during a chemical reaction
The mass of the products stays the same during a chemical reaction
The type and number of atoms in the reactants equals the type and number of atoms in the products
The mass of the products is always twice the mass of the reactants
If the reactants on the left side of a chemical equation are C3H8 + 5O2, the products in a balanced equation could be
4CO3 + 3H2O
3CO2 + 4H2O
2CO2 + 3H2O
3CO + 4H2O
If more reactants are used in a chemical reaction, more products will be produced. This is because
More reactants cause the reaction to heat up
More reactants take up the same volume
More reactants have more atoms to react to form more products
Too many products can slow down the reaction
In a chemical reaction, substance A reacts with substance B and forms a new substance AB. The chemical equation for this reaction is A + B = AB where A and B are the reactants and AB is the product. If you add more and more of only substance A, there will be
Less and less of product AB
More and more of product AB with no limit to the amount of AB produced
No change in the amount of AB produced
More and more of product AB but limited by the amount of B
One clue of a chemical change is the formation of a precipitate. A precipitate is formed when
Two liquids react and a gas is produced
A solid dissolves in a liquid
One liquid dissolves in another
Two liquids react and a solid is formed
In a chemical reaction, if the reactants are heated, the reaction usually happens
Faster
Slower
At the same rate
In a smaller volume
Some chemical reactions require a substance called a catalyst. The main purpose of a catalyst is
To warm up the reaction
To speed up the reaction
To create more reactants
To stop the reaction
