Lab practical 4 - Identification of unknown chloride slts

Question 1

What is the main aim of the chloride salt identification?

Answer 1

deduce chemical formula of 2 unknown salts- deduce what the chlorine in the sat is bound to

Question 2

What are the 3 main parts of the chloride salt identification?

Answer 2

Observation
Titration
Flame test

Question 3

What do solubility rules help determine?

Answer 3

what substances are soluble and to what extent

Question 4

What equipment is needed for the chloride salt identification practical?

Answer 4

Burette & Stand
Beakers and conical flasks
Bunsen burner & stand
Dropper
Nichrome wire for the flame colour tests
Balance
0.6 grams each of 2 unknown chloride salts
DI water
20mL 0.1 M NaCl
100 mL 0.1M AgNO3
5mL 1 % (actually 0.1%) dichlorofluorescein indicator solution in 70% ethanol and 30% deionized water
20mL of 0.1M of Na3PO4

Question 5

What is the first step in the observation of precipitate reactions for the chloride salt identification?(NaCl)

Answer 5

put 1-2 ml 0.1 M NaCl in test tube
drop by drop add 20-30 drop 0.1 M AgNO3 (20 drops)
Record drops added and note observations

Question 6

What is the second step in the observation of precipitate reactions for the chloride salt identification?(dichlorofluorescein)

Answer 6

add 1-2 mL 0.26 M dichlorofluorescein in test tube
Add 0.1 M AgNO3 drop by drop record drops (68 drops)

Question 7

What is the objective of the precipitation reactions to identify the unknown chloride salts?

Answer 7

if precipitate forms when aqueous solutions are mixed of unknown salt and sodium phosphate
Say whether think group 1 or 2

Question 8

How do you prepare the precipitation reactions for the unknown salts? (chloride salt identification)

Answer 8

dissolve approximately 0.1 g salt in 25mL deionized water.
Add 5mL of 0.1M of Na3PO4 to each unknown.

Question 9

What is step 1 for the titration in the chloride salt identification practical? (molarity)

Answer 9

record molarity of AgNO3

Question 10

What are the 4 main steps of the titration for chloride salt identification practical?

Answer 10

Record molarity AgNO3
Determine end point of titration
Determination of molar mass
Theoretical molar masses

Question 11

What is step 1 to determine the end point of the titration in the chloride salt identification? (burette AgNO3)

Answer 11

Fill burette with AgNO3 and record initial volume

Question 12

What is step 2 to determine the end point of the titration in the chloride salt identification? (initial titration)

Answer 12

initial titration with 10mL 0.1 M NaCl and 0.5 mL 0.1 % dichlorofluorescein

Question 13

What is step 3 to determine the end point of the titration in the chloride salt identification? (weigh salt)

Answer 13

weight ~0.1g unknown salt 1

Question 14

What is step 4 to determine the end point of the titration in the chloride salt identification? (dissolve salt )

Answer 14

Place unknown salt into small beaker
Add 25 mL water and thoroughly dissolve salt
Add 0.5 M 0.1% dichlorofluorescein

Question 15

What decimal points should the initial titration of the unknown chloride salt be put to?

Answer 15

2 decimal places

Question 16

What is step 5 to determine the end point of the titration in the chloride salt identification? (titrate )

Answer 16

Titrate salt with silver nitrate to end point
Record volume in the burette
Repeat the steps for both unknown salts 2 times so an average can be generated

Question 17

What must you do for the determination of molar masses for unknown salt practical?

Answer 17

convert net volume to litres then use equation= AgNO3 = (molarity) x (litres)

Question 18

What hint is there for calculating the moles of salt in the unknown samples? (using results from obervations)

Answer 18

If unknown sample contains group 1 salt, the moles salt will equal moles AgNO3. If unknown sample contains group 2 salt, moles salt will equal ½ moles AgNO3

Question 19

What is the formula to find molar mass? (unknown salt practical)

Answer 19

mass of salt / moles of salt

Question 20

How can theoretical molar mass help in the unknown salt practical?

Answer 20

can compare theoretical with observed and say which most likely linked to

Question 21

What is the flame test procedure?

Answer 21

Looped end nichrome wire
Put Bunsen on blue flame
Water in beaker and dip wire in then in salt
Put loop wire in fame and record colour obs