TESTS

Question 1

How do you make a standard solution?

Answer 1

Dissolve solid in a beaker with about 100ml of water, pour into volumetric flask using funnel, rinse beaker, pour that into volumetric flask, fill so bottom of meniscus is on line.

Question 2

How do you do a titration?

Answer 2

Measure 25cm3 tankard solution using volumetric pipette, add to conical flask with 2-3 drops of indicator, fill the indicator w unknown conc, add to conical flask, swirl over white tile till permanent colour change, record volume added to 2dp, repeat. Add drop by drop when beat end point, repeat till consistent results within 0.1.

Question 3

How do you measure mass ?

Answer 3

Weigh full and empty

Question 4

How do measure volumes of solutions ?

Answer 4

Volumetric pipette

Measure from bottom of meniscus

Question 5

How do you measure volumes of gas ?

Answer 5

Gas syringe OR

fill measuring cylinder measure water displaced.

Question 6

How do you test for carbonate ions ?

Answer 6

React with dilute strong acid forming CO2 -limewater

Question 7

How do you test for sulphate ions?

Answer 7

Reaction with Ba2+ forming white precipitate.

Barium nitrate if it’s a test with other tests, barium chloride if not (chloride will interfere with halide test)

Question 8

How do you test for halide ions?

Answer 8

Silver nitrate:
White-Cl-
Cream-Br-
Yellow-I-
Precipitates

Question 9

How do you confirm the test for halide ions ?

Answer 9

Dilute NH3:
White chloride precipitate dissolves.
Conc (dOnT tOUcH tHe ConC) NH3:
Cream (bromide) dissolves.

Question 10

How do you test for ammonium ions ?

Answer 10

React with WARM NaOH

Forming NH3 gas which turns DAMP red litmus blue.

Question 11

How do You see how equilibrium has shifted ?

Answer 11

Changing conditions and then colour changes associated with with reactants/ products can be measured using colorimeter to see how equilibrium has shifted.

Question 12

How do you see the position of equilibrium if there are acids or alkalis in reactants or products?

Answer 12

Change conditions, take a sample of the mixture, and do a titration to find concentration of acid or alkali.

Question 13

How do you dry with an anhydrous salt?

Answer 13

The salt absorbs any water, filter mixture to remove hydrated salt and leave product.

Question 14

Name 2 anhydrous salts.

Answer 14

MgSO4

CaCl2

Question 15

What do you have to be careful with with the ion tests ?

Answer 15

BaCO3 is also a white precipitate

And Ag2SO4

Question 16

What is the order you do the tests ?

Answer 16

1) carbonate
2) sulphate
3) halides

Question 17

FOR TESTS WHAT BACKGROUND ION DO U ALWAYS USE

Answer 17

NO3-