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Flashcards in C3 - Analysis & Synthesis Deck (45)
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1

What are the two main methods for testing for positive ions?

-Flame test
-Reaction with sodium hydroxide.

2

How is a flame test carried out?

-The compound is put on a cleaned wire loop
-The loop is then held in a Bunsen burner.
-The colour of the flame can be used to identify a positive ion.

3

What colour flame does lithium produce?

Crimson

4

What colour flame does sodium produce?

Yellow

5

What colour flame does potassium produce?

Lilac

6

What colour flame does calcium produce?

Red

7

What colour flame does barium produce?

Green

8

What possible elements are present if a white precipitate forms in sodium hydroxide?

Al3+, Ca2+, Mg2+

9

How is it possible to distinguish between Al, Ca and Mg ions?

-Adding more NaOH causes aluminium ions to dissolve.
-Calcium can be identified with a flame test.

10

Which ions produce a blue precipitate with NaOH?

Copper(II)

11

Which ions produce a green precipitate with NaOH?

Iron(II)

12

Which ions produce a brown precipitate with NaOH?

Iron(III)

13

How can negative carbonate ions be identified?

-Adding dilute acid produces CO2 gas.
-Limewater is then turned cloudy.

14

How can negative halide ions be identified?

-Nitric acid then silver nitrate solution is added.
-If a precipitate forms, halides are present.

15

Which ions produce a white precipitate with silver nitrate?

Chloride

16

Which ions produce a cream precipitate with silver nitrate?

Bromide

17

Which ions produce a yellow precipitate with silver nitrate?

Iodide

18

How can negative sulfate ions be identified?

-Hydrochloric acid then barium chloride is added.
-If a white precipitate forms, sulfate ions are present.

19

What is titration used for?

To measure how much acid and alkali react completely.

20

What is the end-point of a reaction?

The point at which the acid and alkali have reacted completely.

21

What is a pipette used for?

Measure out a fixed solution.

22

What is a burette used for?

Measuring the volume added.

23

How is the concentration of a solution calculated?

-Calculate the mass in 1cm3 of solution.
-Calculate mass of solute in 1000cm3 of solution.
-Convert the mass to moles.

24

How is the mass of solute calculated?

-Calculate the mass of the solute in 1dm3.
-Calculate mass in 1cm3.
-Calculate the mass in the given volume.

25

What technique is used to analyse DNA?

Gel electrophoresis

26

Give two examples of chemical analysis in medicine.

-DNA can be matched to find suitable donors.
-Metal concentrations can be analysed to indicate joint failures.

27

What is the point of equilibrium?

When the rate of forward and reverse reactions are equal.

28

What happens when a system of equilibrium is changed?

When a system of equilibrium is subjected to a change then the position of equilibrium will shift to oppose the change.

29

How does changing the pressure affect reversible reactions involving gases?

-Increasing the pressure favours the reaction with the least number of molecules of gas formed.
-Decreasing the pressure favours the reaction with the greater number of molecules of gas formed.

30

How does changing the temperature affect reversible reactions?

-Increasing the temperature favours the endothermic reaction.
-Decreasing the temperature favours the exothermic reaction.