Amount Of Substance Flashcards

0
Q

What is molar mass and what is it’s units?

A

The mass of one mole of something

G mol ^-1

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1
Q

What is the value of a mole and what is this value called?

A

6x10^23

Avogadro’s constant

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2
Q

Calculate the molar mass of Ni(OH)2

A

Mr = 58.7 + (2x(16+1)) = 92.7

92.7 g mol^-1

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3
Q

How do you calculate moles, when conc is not given?

A

Moles = mass of a substance / molar mass

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4
Q

Calculate the moles of CaBr2 in 39.98g

A

0.2 moles

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5
Q

A compound has 0.05 moles and weighs 2.6 g. Find it’s relative molecular mass

A

52

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6
Q

What is the equation of moles when concentration is given?

A

Moles = conc x volume / 1000

When in cm^3

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7
Q

A 0.5 mol dm^-3 solution of ZnSO4 contains 0.08 moles what volume does this occupy?

A

0.16 dm^3

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8
Q

What mass of sodium hydroxide needs to be dissolved in 50cm3 of water to make a 2M solution?

A

4g

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9
Q

What is the equation to work out the mass of a gas (in standard conditions) when only volume is given?

A
Moles = volume / 24 (in dm^3)
Moles = volume / 24000 (in cm^3)
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10
Q

What volume in cm^3 does 0.02 moles of hydrogen gas occupy in standard conditions?

A

= 0.02 x 24000 = 480 cm ^3

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11
Q

What is the ideal gas equation?

A

PV = nRT

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12
Q

At a temperature of 60oC and a pressure of 250KPa a gas occupied a volume of 1100 cm3 and had a mass of 1.6g.

Find it’s relative molecular mass

A

16

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13
Q

Balance the equation

C2H6 + O2 —> CO2 + H2O

A

C2H6 + 3.5O2 —-> 2CO2 + 3H2O

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14
Q

Calculate the mass of iron oxide produced if 28g of iron is burnt in air in this equation:

2Fe + 1.5 O2 —-> Fe2O3

A

40g of iron oxide

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15
Q

What are the state symbols?

A

G , l, S, aq (solution in water)

16
Q

What do you produce when an acid reacts with a an alkali?

A

A Salt and water

17
Q

What can we use titration so to find out?

A

How much acid is needed to neutralise a quantity of alkali
Calculate volumes
Calculate concentrations

18
Q

25cm3 of 0.5M HCL was used to neutralise 35cm3 of NaOH solution. Calculate the concentration of sodium hydroxide and give units

A

0.36 mol dm^-3

19
Q

20.4 cm3 of a 0.5 M solution of Na2CO3 reacts with 1.5 M nitric acid. Calculate the volume of nitric acid needed to neutralise this.

Na2CO3 + 2HNO3 —-> 2NaNo3 + H2O + CO2

A

13.6 cm^3

20
Q

What is empirical formula?

A

The simplest ratio of different atoms in a compound

21
Q

How do we calculate percentage yield?

A

Percentage yield = actual yield / theoretical yield x 100

22
Q

How do we calculate atom economy?

A

Atom economy = mass of desired product / total mass of reactants x 100