chemical reactions Flashcards
1
Q
what is a chemical reaction
A
when atoms rearrange and join together to make a new substance
2
Q
name the 2 things that all chemical reactions do
A
- make new substances
- transfer energy to their surroundings
3
Q
how do you know if a chemical reaction is taking place
A
by using your senses
see- sparks or flames
notice a smell
hear- fizzing or loud bangs
feel-temperature change
4
Q
why are chemical reactions helpful
A
they make things we need e.g medicines, fabrics, building materials
4
Q
what are catalysts
A
a catalyst can speed
up a reaction. A catalyst isn’t used up in the
reaction and different reactions need different catalysts
4
Q
is a chemical change reversible or irreversible
A
irreversible because the atoms are binding to make a new substance.
5
Q
is a physical change reversible or irreversible
A
reversible
