Hi Flashcards
What is a chemical change?
Formation of a new substance
What is effervescence
When a chemical reaction fizzes
What is carbon dioxide gas?
Lumps of chalk are reacting with hydrochloric acid
What is precipitation?
Some reactions between solutions produce a solid
What is precipitate?
The solid formed in precipitation reaction.
What is exothermic reaction?
Reactions that give out heat
What is combustion?
The process of burning sth
What is an endothermic reaction?
Any chemical reaction that absorbs heat from its environment
What is an reactant in a chemical reaction?
The substance we start with in a chemical reaction are called reactants
What is the product?
The new substance formed in a chemical reaction
Why are word equations useful in a chemical reaction?
Word equations are a useful way of describing chemical reactions.
What is a physical change?
Physical changes are different from chemical changes in that no new substance are formed during the change
What are mixing substances?
Mixing substances can be described as a physical change. If no new substances are produced it is usually quite easy to separate the substances in a mixture.
What are the mixtures in air?
A mixture of gases including oxygen, nitrogen, argon and carbon dioxide
What are the mixtures in sea water?
A mixture of water , salt and other dissolved substances
What are the mixtures in soil?
A mixture of rock fragments ,water,dissolved minerals, air and humus