WorksheetsYear 8 End of Unit Chemical reactions
Total questions: 50
Worksheet time: 50mins
When mixing two unknown substances the mixture begins to increase in temperature. Is this evidence of a chemical reaction?
YES
NO
During a lab investigation two substances are mixed together and give off a strange odor. Is this a sign of a chemical reaction?
yes
no
A piece of gold jewelry is melted over a flame and becomes a liquid. Is this a sign of a chemical reaction?
yes
no
Which of the following show signs of a chemical reaction?
Liquid water is boiled to produce steam.
Large brown rocks are ground into smaller pieces to produce a brown powder.
A colorless liquid and a gray solid are mixed to produce a gas and a green liquid.
Water is added to a dark blue liquid to produce a light blue liquid.
Which of the following is an example of a chemical change?
cutting a piece of wood into small wood chips
burning a marshmallow
dissolving table salt in a glass of water
freezing liquid water to produce ice cubes
Which of the following statements is true?
In a chemical reaction, the total mass of the products is more than the total mass of the reactants.
In a chemical reaction, the total mass of the products is less than the total mass of the reactants.
In a chemical reaction, the total mass of the products is unrelated to the total mass of the reactants.
In a chemical reaction, the total mass of the products is equal to the total mass of the reactants.
A student measures out 5 mL of calcium chloride solution into a small container and 5 mL of sodium carbonate solution in another small container. The total mass of both chemicals and the containers they are in is 15.23 g. When the student combined the two clear liquids, a gooey, cloudy precipitate formed. What would the total mass of the products and the two containers be after this reaction took place?
15.20 g
15.23 g
15.25 g
30.46 g
Which of the following is an example of using a chemical process to release energy?
cutting wood into smaller pieces
dissolving copper chloride powder into a beaker of water
using a match to light a candle
heating an ice cube to melt it
The diagram above shows molecules of two substances, A and B, that are mixed together. Which diagram below shows what might happen at the molecular scale if the substances were to undergo a chemical reaction?
A reaction occurs between two liquids. Before the reaction, liquid A is clear and colorless. Liquid B is clear and light blue in color. When the two liquids are combined, a cloudy pale green solution is formed. Which of the following describes what has occurred?
A chemical reaction took place. The properties of the resulting solution are different than the properties of Liquids A and B. In order for a new substance with different properties to form, a chemical reaction must have taken place.
Only a physical reaction occurred where the resulting solution is a mixture of Liquids A and B, and all three have the same physical properties.
A chemical reaction took place where the mass of the reactants were greater than the mass of the product and all three substances have properties that are different from one another.
This is clear evidence of a magical reaction and magic is real everyone!
Which of the following is a list of physical properties?
temperature change when a chemical is added, odor, density
flexibility, reaction with hydrochloric acid, color
density, physical state at room temperature, flexibility
density, bubbling and fizzing, solubility
What is the left part of a chemical equation called?
2 H2 + O2 --> 2 H2O
Yields
Products
Reactants
Chemical Equation
What is the right part of a chemical equation called?
2 H2 + O2 --> 2 H2O
Yields
Products
Reactants
Chemical Equation
Which of the following is classed as a physical change?
Temperature rise
Colour change
Ice melting
Gas being given off
An exothermic reaction is when the temperature of a reaction increases?
True
False
During an endothermic reaction the temperature decreases during the reaction?
True
False
In the summer, the Eiffel Tower is....?
Bigger than in the winter because it contracts
Smaller than in the winter because it contracts
Bigger than in the winter because it expands
Smaller than in the winter because it expands
Which reaction would be the fastest?
Burning a tree trunk
Burning a wooden splint
Burning wood shavings
Burning a forest of trees
Sarah used 10 grams of a catalyst in an experiment. How much of it would have been used up?
5 grams
7.5 grams
10 grams
0 grams
Ice melts at what temperature in degrees celcius?
50
80
100
0
Water boils at what temperature in degrees celcius?
85
95
105
100
In an endothermic reaction, energy is _________.
absorbed
released
_____ reactions usually feel hot!
endothermic
exothermic
____ reactions usually feel cold.
endothermic
exothermic
Solid --> liquid --> gas is what type of reaction?
endothermic
exothermic
catalytic
inhibited
gas --> liquid --> solid is what type of reaction?
endothermic
exothermic
catalytic
inhibited
Endo means in or _______.
absorbed
released
Exo means out or ________.
absorbed
released
In a reaction A + B ----> C, reactant A has 5g and product C has 9g. How many grams does reactant B have?
4g
5g
9g
14g
