Topic 5 Amount Of Substance

Question 1

What number is 1 mole

Answer 1

6.02x10^23

Question 2

Ideal gas equation and what each letter means

Answer 2

pV=nRT
p= pressure in pascals
V = volume in m^3
n= moles
R = gas constant 8.31
T = temp in kelvins

Question 3

Units for volume in ideal gas equation

Answer 3

m^3

Question 4

What’s the difference between hazards and risks

Answer 4

Hazards could cause harm - risks are likely hazards

Question 5

5 examples of risks in experiments

Answer 5

• scalding from hot liquids
• burn from hot equipment
• burns from chemicals
• cuts from glass
• poisonous or toxic gases or chemicals

Question 6

How to make a standard solution (6 steps)

Answer 6

1) Weight a known mass of solid, 2) Transfer into beaker and wash leftover solid using deionised water,
3) dissolve fully and stir in a beaker 4)transfer to volumetric flask with washings of beaker and glass rod 5) fill to line 6)invert to mix

Question 7

How do you find uncertainty from a piece of equipment

Answer 7

1/2 the smallest measurement

Question 8

When do you double uncertainty

Answer 8

When you take 2 measurements

Question 9

Percentage error formula

Answer 9

Uncertainty/final value * 100

Question 10

How to reduce percentage uncertainty (2 ways)

Answer 10

1) Decrease original uncertainty
2) use higher volumes

Question 11

What’s a systematic error

Answer 11

Repeat errors from faults in method ie. Balance weighs 1g too much each time