Nuri was doing an experiment. He has noted his observation in a table. Test Methods Observation Conclusion 1 Add 1 drop of sodium hydroxide to iron (lll) sulphate A rust-coloured solid appeared. _____ 2 Add 1 drop of sodium hydroxide to calcium chloride A white solid appeared. _____ 3 Heat copper metal in a flame The metal went black _____ 4 Add copper metal to hydrochloric acid. No changes observed. _____ 5 Add magnesium metal to hydrochloric acid. Bubbles are seen coming off of the metal. _____ Complete the table. Write a conclusion for each experiment based on the observations.

Sodium hydroxide and iron III oxide react together and precipitates a rust-coloured substance, iron hydroxide and a sodium sulphate solution. It undergoes a double displacement reaction. Sodium hydroxide when reacts with calcium chloride undergoes a double displacement reaction and forms a white solid, calcium hydroxide and a solution of sodium chloride. When copper metal is heated in a flame it reacts with oxygen and gets oxidised, and forms copper oxide. The black layer of copper oxide is observed on the surface of the metal. Copper is the less reactive metal and is placed below hydrogen in a reactivity series. It does not show any displacement reaction. Magnesium is a reactive metal and is placed above the hydrogen in a reactivity series. It displaces hydrogen from the acid and forms magnesium chloride. It is a displacement reaction. Test Methods Observation Conclusion 1 Add 1 drop of sodium hydroxide to iron (lll) sulphate. A rust-coloured solid appeared. It forms iron hydroxide and shows double displacement reaction. 2 Add 1 drop of sodium hydroxide to calcium chloride. A white solid appeared. It forms calcium hydroxide and shows double displacement reaction. 3 Heat copper metal in a flame. The metal went black. Copper gets oxidised and forms copper oxide. 4 Add copper metal to hydrochloric acid. No changes observed. It doesn't show any displacement reaction as copper is less reactive than hydrogen. 5 Add magnesium metal to hydrochloric acid. Bubbles are seen coming off of the metal. It shows a displacement reaction and forms magnesium chloride with the evolution of hydrogen gas.

Nuri was doing an experiment. He has noted his observation in a table. Methods Observation Add 1 drop of sodium hydroxide to iron (lll) sulphate A rust-coloured solid appeared. Write a word equation for the reaction.

Sodium hydroxide and iron III oxide react together and forms rust-coloured iron hydroxide and a sodium sulphate solution. The word equation for the reaction is as follows: sodium hydroxide + iron III sulphate → iron hydroxide + sodium sulphate

Nuri was doing an experiment. He has noted his observation in a table. Methods Observation Add 1 drop of sodium hydroxide to calcium chloride A white solid appeared. Write a word equation for the reaction.

Sodium hydroxide when reacts with calcium chloride undergoes a double displacement reaction and forms a white solid calcium hydroxide and a solution of sodium chloride. The word equation for the reaction is as follows: sodium hydroxide + calcium chloride → calcium hydroxide + sodium chloride

Nuri was doing an experiment. He has noted his observation in a table. Methods Observation Heat copper metal in a flame The metal went black Write a word equation for the reaction.

When copper metal is heated in a flame it reacts with oxygen and gets oxidised, and forms copper oxide. The black layer of copper oxide is observed on the surface of the metal. The word equation for the reaction is as follows: copper + oxygen → copper oxide

Nuri was doing an experiment. He has noted his observation in a table. Methods Observation Add copper metal to hydrochloric acid. No changes observed. Write a word equation for the reaction.

Copper is the less reactive metal and is placed below hydrogen in a reactivity series. It does not show any displacement reaction. The word equation for the reaction is as follows: copper metal + hydrochloric acid → no change

Nuri was doing an experiment. He has noted his observation in a table. Methods Observation Add magnesium metal to hydrochloric acid. Bubbles are seen coming off of the metal. Write a word equation for the reaction.

Magnesium is a reactive metal and is placed above the hydrogen in a reactivity series. It displaces hydrogen from the acid and forms magnesium chloride. The word equation for the reaction is as follows: magnesium + hydrochloric acid → magnesium chloride + hydrogen gas

When sodium hydroxide is added to a solution of iron (lll) chloride, the following can be seen: A rust coloured solid is formed. The total mass does not change. Explain the observations. Your answer should include a word equation.

Sodium hydroxide and iron III oxide react together and forms rust-coloured iron hydroxide and a sodium sulphate solution. The word equation for the reaction is as follows: sodium hydroxide + iron III sulphate → iron hydroxide + sodium sulphate Chemical reactions follow the law of conservation of mass. The law states that in a chemical reaction the mass of the products formed is equal to the mass of reactants. Hence, the mass total mass does not change, and it is conserved. The total mass of sodium hydroxide and iron III oxide = The total mass of sodium sulphate and iron hydroxide.

EASY

Lower Secondary Stage 8

IMPORTANT

Earn 100

Magnesium metal burns with a bright white light. At the end of the reaction, white magnesium oxide powder is produced. Suggest why magnesium is often found in fireworks. Your answer should include a word equation.

Important Questions on Chemical Reactions

HARD

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 10

Nuri was doing an experiment. He has noted his observation in a table.

Test	Methods	Observation	Conclusion
$1$	Add $1$ drop of sodium hydroxide to iron (lll) sulphate	A rust-coloured solid appeared.	_____
$2$	Add $1$ drop of sodium hydroxide to calcium chloride	A white solid appeared.	_____
$3$	Heat copper metal in a flame	The metal went black	_____
$4$	Add copper metal to hydrochloric acid.	No changes observed.	_____
$5$	Add magnesium metal to hydrochloric acid.	Bubbles are seen coming off of the metal.	_____

Complete the table. Write a conclusion for each experiment based on the observations.

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 10

Nuri was doing an experiment. He has noted his observation in a table.

Methods	Observation
Add $1$ drop of sodium hydroxide to iron (lll) sulphate	A rust-coloured solid appeared.

Write a word equation for the reaction.

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 10

Nuri was doing an experiment. He has noted his observation in a table.

Methods	Observation
Add $1$ drop of sodium hydroxide to calcium chloride	A white solid appeared.

Write a word equation for the reaction.

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 10

Nuri was doing an experiment. He has noted his observation in a table.

Methods	Observation
Heat copper metal in a flame	The metal went black

Write a word equation for the reaction.

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 10

Nuri was doing an experiment. He has noted his observation in a table.

Methods	Observation
Add copper metal to hydrochloric acid.	No changes observed.

Write a word equation for the reaction.

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 10

Nuri was doing an experiment. He has noted his observation in a table.

Methods	Observation
Add magnesium metal to hydrochloric acid.	Bubbles are seen coming off of the metal.

Write a word equation for the reaction.

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 1>Q 11

When sodium hydroxide is added to a solution of iron (lll) chloride, the following can be seen:

A rust coloured solid is formed.
The total mass does not change.

Explain the observations. Your answer should include a word equation.

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Workbook>Chapter 6 - Chemical Reactions>Exercise 2>Q 1

Name the compounds produced when hydrochloric acid reacts with calcium oxide.

Magnesium metal burns with a bright white light. At the end of the reaction, white magnesium oxide powder is produced. Suggest why magnesium is often found in fireworks. Your answer should include a word equation.

Important Questions on Chemical Reactions

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