Reactions

Question 1

when does a chemical reaction occur

Answer 1

when atoms are rearranged to make new substance
almost like taking a boat made out of lego apart and using those pieces to make a plane

Question 2

are chemical reactions easily reversible

Answer 2

no
for example if you burn toast you cant unburn it which is the same for chemical reaction

Question 3

when do you know a chemical reaction has taken place

Answer 3

• colour change
• a gas is released (fizzing)
• there is a smell

Question 4

what are acids and alkalis used for

Answer 4

• acid can be used in some foods
• alkalis are often used in some cleaning products

Question 5

where do acids and alkalis belong

Answer 5

belong on the pH scale which foes from 1 - 14 7 is neutral, water is nuetral

Question 6

State the definition of chemical reaction

Answer 6

chemical change where atoms can bond together to form new products

Question 7

Define acid

Answer 7

substance with a ph 7, has H* ions

Question 8

Define alkali

Answer 8

substance with a ph 7, has OH ions

Question 9

Define neutralisation

Answer 9

reaction with acid and alkali — salt and water

Question 10

Define base

Answer 10

an alkali that does not dissolve in water

Question 11

crystalisation

Answer 11

method of separation to separate a dissolved salt from a solution

Question 12

what happens when an acid and alkali react together

Answer 12

they form a salt and water

Question 13

what is the salt always named by

Answer 13

metal in the alkali and the type of acid

Question 14

name some of the typical properties of metals

Answer 14

• good conductor of electricity
• good conductor of heat
• shiny
• high density (heavy for its size)
• malleable (you can hammer it into shapes)

Question 15

name some of the typical properties of non metals

Answer 15

• poor conductor of electricity
• poor conductor of heat
• dull
• low density (light for its size)
• brittle (breaks easily)

Question 16

what happens when metals react with acids

Answer 16

they form a salt and hydrogen gas is given off. The
salt is named the same as in
neutralisation, the metal + the naming
portion of the acid. So for iron and
sulfuric acid, it would make iron sulfate.

Question 17

when do oxidation reactions happen

Answer 17

usually between a metal element and oxygen, this is what happens to your bike if you leave it outside.

Question 18

what does the periodic table include

Answer 18

all objects known to man. Everything in the entire universe is made from these ingredients

Question 19

what is a large quantity of your blood made out of

Answer 19

iron and metal

Question 20

what happens when metal react with water

Answer 20

metal hydroxides are formed as well as hydrogen gas. Some do not react with liquid water and must be reacted with steam