YEAR 7
Chemistry Chapter 3
Reactions
3.1 Chemical reactions
GLOSSARY :
Chemical reactions :
A change in which atoms are rearranged to create new substance .
Catalyst :
Any substance that increases the rate of a reaction without itself being consumed.
Physical change :
A change that is reversible in which new substances are not made , examples of
physical changes include changes of state and dissolving.
1
, 3.1 Assessment
Q.1 : Explain what are chemical reactions ? state 2 common things happen
in all chemical reactions .
Q.2 : Why most chemical reactions are not easily reversible ?
Q.3 : State at least 3 evidences that tells you in a lab chemical reactions
are happening .
Q.4: State 3 examples of useful products made in chemical reactions .
2
, Q.5: Give 2 examples of Not useful chemical reaction .
Q.6 Choose the correct answer
Chemical reaction involve re-arranging ( states - atoms )
Chemical reactions ( always - sometimes ) make new substance
They ( are - are not ) easily reversible .
They ( always - never ) involve energy transfer
Physical reaction include changes of ( substance - state ) the ( are - are not )
reversible .
Q.7 Which of the changes listed below are chemical changes , and which are
physical changes .
- Burning diesel to make carbon dioxide and water ................................
- Dissolving sugar in a tea to make it more sweet .....................................
3
Chemistry Chapter 3
Reactions
3.1 Chemical reactions
GLOSSARY :
Chemical reactions :
A change in which atoms are rearranged to create new substance .
Catalyst :
Any substance that increases the rate of a reaction without itself being consumed.
Physical change :
A change that is reversible in which new substances are not made , examples of
physical changes include changes of state and dissolving.
1
, 3.1 Assessment
Q.1 : Explain what are chemical reactions ? state 2 common things happen
in all chemical reactions .
Q.2 : Why most chemical reactions are not easily reversible ?
Q.3 : State at least 3 evidences that tells you in a lab chemical reactions
are happening .
Q.4: State 3 examples of useful products made in chemical reactions .
2
, Q.5: Give 2 examples of Not useful chemical reaction .
Q.6 Choose the correct answer
Chemical reaction involve re-arranging ( states - atoms )
Chemical reactions ( always - sometimes ) make new substance
They ( are - are not ) easily reversible .
They ( always - never ) involve energy transfer
Physical reaction include changes of ( substance - state ) the ( are - are not )
reversible .
Q.7 Which of the changes listed below are chemical changes , and which are
physical changes .
- Burning diesel to make carbon dioxide and water ................................
- Dissolving sugar in a tea to make it more sweet .....................................
3
