acids, alkalis + salts (paper 1)

Question 1

acid definition

Answer 1

• produce hydrogen ions in water
• proton donors
• acid solutions have a pH <7

Question 2

base definition

Answer 2

• can neutralise an acid
• proton acceptors

Question 3

alkali definition

Answer 3

• soluble bases
• produce hydroxide ions in water
• Have a pH >7

Question 4

when will an indicator not work?

Answer 4

when the solution has a colour

Question 5

what will metal oxides form?

Answer 5

alkaline solutions

Question 6

what do non-metal oxides form?

Answer 6

acidic solutions

Question 7

MASH

Answer 7

metal + acid —–> salt + hydrogen

Question 8

base word equation

Answer 8

metal oxide + acid —–> salt + water

Question 9

metal carbonate word equation

Answer 9

metal carbonate + acid —-> salt + carbon dioxide + water

Question 10

alkali word equation

Answer 10

metal hydroxide + acid —-> salt + water

Question 11

phosphoric acid in universal indicator

Answer 11

red

Question 12

lithium hydroxide in universal indicator

Answer 12

purple

Question 13

ammonia in universal indicator

Answer 13

light blue

Question 14

vinegar in universal indicator

Answer 14

orange

Question 15

methyl orange in acid and alkali

Answer 15

acid = red
alkali = yellow

Question 16

bromothymol in acid and alkali

Answer 16

acid = yellow
alkali = blue

Question 17

how do you make salts? - excess solid method (7 marks)

Answer 17

1. heat the sulphuric acid
2. add black CuO to excess and stir
3. filter out excess CuO
   4+5. heat the CuSO4 (blue) solution until crystallization point and leave to cool
4. filter out crystals and wash with distilled water
5. leave to dry/dry with filter paper

Question 18

The student uses a titration method to add ammonium hydroxide solution to the acid until the reaction reaches its end point, which is shown by a change in colour of an indicator in the solution. The student then crystallises the solution to obtain a salt. Will this produce a pure sample pf the salt? Explain your answer.

Answer 18

No because the salt will be contaminated by the indicator

Question 19

define a precipitate

Answer 19

insoluble salt made from 2 solutions

Question 20

is sodium potassium and ammonium soluble or insoluble?

Answer 20

soluble

Question 21

are nitrates soluble or insoluble?

Answer 21

soluble

Question 22

are chlorides soluble or insoluble?

Answer 22

soluble
except silver chloride + lead chloride

Question 23

are sulfates soluble or insoluble?

Answer 23

soluble
except lead barium + calcium sulfate

Question 24

are carbonates soluble or insoluble?

Answer 24

insoluble
except sodium potassium + ammonium

Question 25

are hydroxides soluble or insoluble?

Answer 25

insoluble
except sodium potassium + ammonium

Question 26

what is a titration and how would you carry one out? (6 marks)

Answer 26

1. allow you to find out how much acid is needed to neutralize a quantity of acid or alkali
2. using pipette + pipette filler add 25cm^3 of alkali to a conical flask with 2-3 drops of indicator
3. fill burette with acid below eye level
4. using the burette add acid to the alkali bit at a time giving conical flask regular swirl. Go slowly when end point is about to be reached
5. indicator changes colour when all the alkali has been neutralized
6. record volume of acid used to neutralize the alkali