2.1.4 Acids

Question 1

what is the formula for ethanoic acid?

Answer 1

CH3COOH

Question 2

what is the formula for sodium carbonate?

Answer 2

Na2CO3

Question 3

what is the formula for phosphoric acid?

Answer 3

H3PO4

Question 4

what is the definition of an acid?

Answer 4

in water an acid releases hydrogen ions into solutions (a proton donor)

Question 5

what is the definition of a hydrogen ion?

Answer 5

a hydrogen ion has no electrons in its outer shell , it is known as a proton

Question 6

what is the definition of a strong acid?

Answer 6

a strong acid releases all of its hydrogen ions in the solution and is completely dissociated / ionised

Question 7

what is the definition of a weak acid?

Answer 7

a weak acid only releases a small number of its hydrogen ions in solution and partially dissociates / ionises

Question 8

when a strong acid dissociates is it a reversible reaction?

Answer 8

NO

Question 9

when a weak acid dissociates is it a reversible reaction?

Answer 9

YES

Question 10

what is the definition of a base?

Answer 10

a compound that neutralises an acid, by accepting a hydrogen ion, to form a salt (proton acceptor)

Question 11

what are bases usually?

Answer 11

metal oxides or ammonia

Question 12

how do bases form dative covalent bonds?

Answer 12

bases donate 2 electrons to the hydrogen ion to form a dative covalent bond

bases can either have a lone pair or negative charge

Question 13

what is the definition of an alkali?

Answer 13

an alkali is a soluble base that releases hydroxide ions

Question 14

give examples of common alkalis used

Answer 14

hydroxides

NaOH

KOH

Ca(OH)2

Question 15

what is the definition of a salt?

Answer 15

a salt is the product of a reaction in which H+ ions from the acid are replaced by the metal or ammonium ions

Question 16

what does a metal + acid make?

Answer 16

salt + hydrogen

Question 17

what does a metal oxide (base) + acid make?

Answer 17

salt + water

Question 18

what does a metal hydroxide + acid make?

Answer 18

salt + water

Question 19

what does a metal carbonate + acid make?

Answer 19

salt + carbon dioxide + water

Question 20

what does ammonia + acid make?

Answer 20

ammonium salt

Question 21

what is the method for making a standard solution?

Answer 21

1 - weigh out the mass of the solid using weigh by difference to 2 decimal places

2 - place the solid into a beaker

3 - add 10cm3 of distilled water to the beaker

4 - stir the solution to dissolve the solid

5 - transfer the solution to a 250cm3 volumetric flask

6 - rinse the equipment into the volumetric flask

7 - make up the solution to the 250cm3 line with distilled water, using a pipette, the bottom of the meniscus should be on the line

8 - put on the lid and invert several times to mix

Question 22

what are concordant results?

Answer 22

results within 0.1cm3 of each other

Question 23

what results must you only use in the titration calculation?

Answer 23

concordant results

do not use rough

Question 24

what is the equation for the titration calculation?

Answer 24

moles = conc x volume
———————-
1000

Question 25

what are the steps for the titration calculation?

Answer 25

1 - moles

2 - ratio

3 - apply to question

Question 26

what is the method for a titration?

Answer 26

1 - rinse all glass wear with distilled water and the solution that will be used

2 - measure 25cm3 of the standard solution with a pipette and filler and put in conical flask

3 - add 3 drops of indicator

4 - place on white tile

5 - using a funnel fill the biurette with acid, to the zero mark with the bottom of the meniscus on this line

6 - complete a rough titration, looking for the end point while swirling the conical flask

7 - repeat the experiment adding the acid drop by drop to reach the endpoint

8 - rinse conical flask between titrations with distilled water

9 - record out titres into a table

10 - calculate the mean titre using concordant results