WorksheetsChemical Reactions
Total questions: 70
Worksheet time: 58mins
Water (H2O) is a compound but hydrogen (H2) is not because:
Water consists of two different elements chemically combined, while hydrogen consists of only one element.
Both water and hydrogen consist of only one element.
Hydrogen is a compound and water is an element.
Water and hydrogen are both compounds.
A solution is made by:
Mixing a solute in a solvent until it is evenly distributed
Heating a solute until it melts
Freezing a solvent
Evaporating the solute
The opposite of melting is:
boiling
freezing
evaporation
condensation
Explain how to make a solution.
What is the opposite of melting? Explain.
freezing because it turns the liquid back into a solid
boiling because it turns the liquid into a gas
evaporation because it changes liquid to vapor
condensation because it turns gas into liquid
Freezing is a physical change because:
it changes the chemical composition of the substance.
it only changes the state of matter from liquid to solid without changing the chemical composition.
it creates a new substance.
it involves a chemical reaction.
The word equation for the reaction of oxygen and hydrogen, which makes water, is:
oxygen + hydrogen → water
hydrogen + water → oxygen
water + oxygen → hydrogen
hydrogen + oxygen → carbon dioxide
Which two observations can be made when wood burns?
Flames and smoke are produced
Water is formed and temperature decreases
Wood becomes colder and turns white
No change is observed
5. How can you tell that freezing is a physical change?
It is reversible (melting)
It creates a new substance
It changes the chemical composition
It cannot be undone
The hazard symbol for an irritant is usually:
A skull and crossbones inside a diamond
A flame inside a diamond
An exclamation mark (!) inside a diamond-shaped border
A gas cylinder inside a diamond
Name two acids and two alkalis.
acids: citric acid / stomach acid; alkalis: bleach / soap / toothpaste
acids: vinegar / lemon juice; alkalis: orange juice / milk
acids: water / salt; alkalis: sugar / oil
acids: baking soda / ammonia; alkalis: hydrochloric acid / sulfuric acid
How is a strong acid different to a weak acid?
strong acid: all the particles split up; weak acid: only a few particles split up
strong acid: only a few particles split up; weak acid: all the particles split up
strong acid: does not react with metals; weak acid: reacts with metals
strong acid: tastes bitter; weak acid: tastes sour
During chemical reactions, atoms are rearranged and new substances are formed.
True
False
Which of the following has the lowest pH value?
Stomach acid
Water
Soap
Milk of magnesia
Which of the following is a non-metal according to the periodic table shown?
Sodium (Na)
Iron (Fe)
Oxygen (O)
Copper (Cu)
Match the following pH values to the correct substance:
Water
C
Bleach
A
Lemon
B
What safety equipment is shown in the image that should be worn during chemical reactions?
Safety goggles
Sandals
Wool gloves
Baseball cap
Arrange the steps in the correct order for preparing a salt from an acid and an insoluble base:
Add insoluble base in excess, mix to react
Heat acid in water bath
Filter to remove unreacted base
Gently heat to evaporate water
Leave to crystallise, wash and dry
According to the image, what do acids and alkalis react to form?
Acid and Base
Salt and Water
Metal and Gas
Fire and Smoke
The pH scale shows that a pH of 7 is _________
neutral
acidic
basic
alkaline
What is a chemical reaction?
What is a reactant?
Substance we start with.
Substance we end with.
A type of energy.
A laboratory tool.
What is a product in a chemical reaction?
Substance which is formed/made.
Substance which is used up.
A type of catalyst.
A type of energy.
Which of the following is an observation that indicates a chemical reaction has occurred?
Change in colour
Fizzing
Flames
All of the above
What is a physical change?
Reversible changes (e.g. dissolving, melting) which aren’t reactions.
A change that creates a new substance.
A process that cannot be reversed.
A chemical reaction that produces heat.
What is an acid?
What is an alkali or base?
If a solution has a high concentration, what does it mean?
It has lots of acid/alkali particles and few water particles.
It has very few acid/alkali particles and lots of water particles.
It contains only water and no acid/alkali particles.
It has equal amounts of acid/alkali particles and water particles.
What does it mean if an acid is strong?
What is a hazard of strong or concentrated acids/alkalis?
Corrosive.
Flammable.
Radioactive.
Magnetic.
What precaution should you take when handling acids and alkalis?
Wear gloves and goggles to protect skin and eyes.
Taste the chemicals to identify them.
Mix acids and alkalis with bare hands.
Ignore safety instructions as they are unnecessary.
What colour does red litmus turn in alkali?
Blue.
Red.
Green.
Yellow.
What colour does blue litmus turn in acid?
Red.
Blue.
Green.
Yellow.
What does a universal indicator show?
How strong or weak an acid or alkali is.
The temperature of a solution.
The amount of salt in water.
The volume of a liquid.
Lower pH values mean more ________.
acidic
basic
neutral
alkaline
Higher pH values mean more ________.
alkaline
acidic
neutral
salty
What is a neutralisation reaction?
Which of the following is a product of sodium hydroxide and hydrochloric acid?
Sodium chloride
Copper nitrate
Calcium sulfate
Nitric acid
What is the use of indigestion tablets in terms of neutralisation?
Indigestion tablets are a base which neutralises stomach acid.
Indigestion tablets increase the acidity of the stomach.
Indigestion tablets are an acid which neutralises stomach base.
Indigestion tablets help in the absorption of more acid in the stomach.
What is the first step in making a salt as shown in the diagram?
Filter to remove left over unreacted solid base
Add base to acid until some base is left over
Heat solution to evaporate most of the water
Leave in a warm place to get dry salt crystals
What is the periodic table?
What is a chemical symbol?
Where are metals found on the periodic table?
On the left/centre of the table.
On the top right of the table.
Only at the bottom of the table.
Scattered randomly throughout the table.
Where are non-metals found on the periodic table?
On the right of the periodic table.
In the center of the periodic table.
On the left of the periodic table.
At the bottom of the periodic table.
What is the main difference in the equation of a chemical reaction vs a physical change?
A chemical reaction involves a change in chemical composition, forming new substances, while a physical change does not alter the chemical composition.
A chemical reaction only changes the state of matter, while a physical change creates new substances.
A chemical reaction does not involve energy changes, while a physical change always releases energy.
A chemical reaction can be reversed easily, while a physical change cannot be reversed.
What is the main difference in the observations of a chemical reaction vs a physical change?
What is a chemical reaction?
A process in which some substances change into different substances.
A process in which substances remain the same.
A process in which substances disappear.
A process in which substances are mixed but do not change.
When wood burns, it undergoes a chemical reaction and forms _________.
ash, soot, water vapour, and carbon dioxide
only water vapour
only oxygen and nitrogen
only ash and water
Which of the following is the starting material in the chemical reaction shown in the image?
Ash
Soot
Wood
Water vapour
What are the products formed when a log of wood is burnt?
Only ash
Only smoke
Smoke, ash, and water vapor
Only water vapor
According to the passage and diagram, if all the smoke, ash, and water vapor from burning a log could be collected, the total mass would be (a) to the mass of the original log.
When a log is burnt, it loses mass because some of its products escape into the air as smoke and water vapor.
True
False
In the chemical equation: carbon dioxide + water → sugar + oxygen, what are the reactants?
carbon dioxide and water
sugar and oxygen
carbon dioxide and oxygen
water and sugar
In the chemical equation: hydrogen peroxide → water + oxygen, what are the products?
water and oxygen
hydrogen and oxygen
water and hydrogen
hydrogen and carbon dioxide
What are the starting substances in a chemical reaction called?
Products
Reactants
Catalysts
Enzymes
What are the ending substances in a chemical reaction called?
Reactants
Products
Catalysts
Enzymes
The two reactants in the chemical equation are ________ and ________.
iron and oxygen
iron and hydrogen
oxygen and carbon
hydrogen and nitrogen
The product formed in the chemical equation is ______.
iron oxide
sodium chloride
carbon dioxide
water
Which of the following is the correct chemical equation shown in the image?
iron + oxygen → iron oxide
iron + water → iron oxide
iron + oxygen → water
iron + hydrogen → iron oxide
Given the reaction: nitrogen + hydrogen → ammonia Name the reactant(s): ________
nitrogen and hydrogen
ammonia and hydrogen
ammonia and nitrogen
only ammonia
Given the reaction: nitrogen + hydrogen → ammonia Name the product(s): ________
ammonia
nitrogen dioxide
water
methane
Given the reaction: lithium nitrate → lithium oxide + nitrogen dioxide + oxygen How many reactants are there? ________
(lithium nitrate)
(lithium nitrate and lithium oxide)
(lithium nitrate, nitrogen dioxide, and oxygen)
(lithium nitrate, lithium oxide, nitrogen dioxide, and oxygen)
Given the reaction: lithium nitrate → lithium oxide + nitrogen dioxide + oxygen How many products are there? ________
3 (lithium oxide, nitrogen dioxide, oxygen)
2 (lithium oxide, nitrogen dioxide)
4 (lithium oxide, nitrogen dioxide, oxygen, lithium nitrate)
1 (lithium oxide)
Which of these show a chemical equation?
weight = mass x gravitational field strength
copper + oxygen = copper oxide
calcium carbonate → calcium oxide + carbon dioxide
carbon + oxygen → carbon dioxide
sulfur and zinc chloride = sulfur chloride and zinc
There are many different types of reaction. Which one has 2 products from 2 reactants?
Combination reaction
Decomposition reaction
Displacement reaction
Double displacement reaction
Q shows:
Breaks one reactant into two products.
Combines two reactants into one product.
Changes the state of a substance.
Transfers energy between substances.
In a reaction the reactants are iron and oxygen. The product formed is iron oxide. Write the word equation for this reaction.
iron + oxygen → iron oxide
iron + hydrogen → iron oxide
iron + oxygen → iron chloride
iron + carbon → iron oxide
In another reaction the product formed is sodium chloride. It was formed from sodium and chlorine. Write the word equation for this reaction.
sodium + chlorine → sodium chloride
sodium + oxygen → sodium chloride
sodium + chlorine → sodium oxide
sodium + hydrogen → sodium chloride
Write the chemical equation for the reaction of hydrogen and oxygen which produces water.
hydrogen + oxygen → water
hydrogen + nitrogen → ammonia
carbon + oxygen → carbon dioxide
sodium + chlorine → sodium chloride
sodium + water → sodium hydroxide + hydrogen Name a product in this reaction:
sodium hydroxide
sodium chloride
potassium hydroxide
magnesium oxide
