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Amount of substance Flashcards

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1
Q

What is the relative atomic mass of an atom?

A

The average mass of an atom of an element (taking into account its naturally occurring isotopes)4 relative to 1/12 the relative atomic mass of an atom of carbon-12

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2
Q

What is the relative molecular mass of a molecule?

A

The mass of a molecule compared to 1/12 the relative atomic mass of an atom of carbon-12

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3
Q

How are the number of moles of a substance established from its mass?

A

Moles = mass/Mr

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4
Q

How many moles are in Xg of Y?

A

X/Mr of Y

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5
Q

How many moles are there in 4.00 kg of CuO

A

50.3

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6
Q

How many moles are there in 39.0 g of Al(OH)3

A

0.5

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7
Q

How many moles are there in 1 tonne of NaCl

A

17100

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8
Q

How many moles are there in 20.0 mg of Cu(NO3)2

A

0.000107

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9
Q

What is the mass of 0.200 moles of Al2O3

A

20.4g

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10
Q

What is the mass of 0.00200 moles of (NH4)2SO4

A

0.264 g

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11
Q

What is the mass of 0.300 moles of Na2CO3.10H2O

A

85.8 g

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12
Q

Calculate the number of moles of Al3+ ions in 5.10 g of Al2O3.

A

0.1

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13
Q

It was found that 1.00 g of vitamin C contains 0.00568 moles of Vitamin C molecules. Calculate the Mr of vitamin C.

A

176

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14
Q

0.8500 g of hexanone, C6H12O, is converted into its 2,4-dinitrophenylhyrazone during its analysis. After isolation and purification, 2.1180 g of product C12H18N4O4 are obtained. Calculate the percentage yield.

A

88.40%

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15
Q

What is the mass of X moles of Y?

A

X x Mr of Y

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16
Q

X moles of a substance has a mass of Y. What is its Mr?

A

Y/X

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17
Q

In what molar ratio do hydrochloric acid with calcium hydroxide react?

A

One to two

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18
Q

In what molar ratio do nitric acid with ammonia react?

A

One to one

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19
Q

What mass of aluminium reacts with 258 mg of chlorine? 2Al + 3Cl2 → 2AlCl3

A

0.0654g

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20
Q

In what molar ratio do sulfuric acid with barium hydroxide react?

A

One to One

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21
Q

In what molar ratio do nitric acid and pottasium carbonate react?

A

Two to One

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22
Q

“Deduce the limiting reagent and calculate what mass of magnesium oxide is formed when 486 mg of
magnesium reacts with 240 mg of oxygen 2Mg + O2 → 2MgO”

A

Oxygen. 0.605g

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23
Q

What is the atom economy of a reaction?

A

A ratio of the mass of desired product to the mass of all products

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24
Q

How is atom economy calculated?

A

(Mr or mass of desired product/Mr or mass of all products) x 100

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25
Q

What is the atom economy to make tungsten in this reaction: WO3 + 3H2 → W + 3H2O

A

77.30%

26
Q

“Calculate the mass of aluminium oxide that would be formed when 2.70 g of aluminium reacts with
2.56 g of oxygen.4Al + 3O2 → 2Al2O3”

A

5.10g

27
Q

At 273 K and 101000 Pa, 6.319 g of a gas occupies 2.00 dm3 . Calculate the relative molecular mass of the gas.

A

71

28
Q

Calculate the atom economy when titanium is extracted from titanium chloride. TiCl4 + 2Mg → Ti + 2MgCl2

A

20.10%

29
Q

What standard units are used for concentration of a solution?

A

mol/dm3

30
Q

How are cm³ converted to dm³?

A

Divide by 1000

31
Q

What are concordant titres?

A

Titres within 0.1cm³ of each other

32
Q

What colour is phenolphthalein in acid and alkali?

A

Colourless in acid, purple in alkali

33
Q

State the ideal gas equation

A

PV = nRT

34
Q

What is the empirical formula of a substance?

A

The formula that represents the simplest whole number ratio of the atoms of each element present in the compound.

35
Q

What is the molecular formula?

A

The actual number of atoms of each element in one molecule of a compound

36
Q

What is an ionic equation?

A

A simplified equation showing the ions present in a reaction

37
Q

What is a spectator ion?

A

An ion that does not take part in a reaction

38
Q

Which substances produce ions in ionic equations?

A

Aqueous solutions of ionic compounds

39
Q

“Write an ionic equation, including state symbols, for the reaction of aqueous ammonia with hydrochloric acid
“

A

H+(aq) + NH3(aq) → NH4+(aq)

40
Q

Write an ionic equation, including state symbols for the precipitation of lead(II) bromide when aqueous lead(II) nitrate is mixed with aqueous sodium bromide

A

Pb2+(aq) + 2Br–(aq) → PbBr2(s)

41
Q

“Write an ionic equation, including state symbols, for the reaction of potassim carbonate solution with nitric acid
“

A

H+(aq) + CO32-(aq) → H2O + CO2(g)

42
Q

Write an ionic equation, including state symbols for the precipitation of lead(II) iodide when aqueous lead(II) nitrate is mixed with aqueous potassium iodide

A

Pb2+(aq) + 2Br–(aq) → PbBr2(s)

43
Q

What volume of carbon dioxide gas, measured at 800 K and 100 kPa, is formed when 1.00 kg of propane is burned in a good supply of oxygen? C3H8 + 5 O2 → 3 CO2 + 4 H2O

A

4.53 m3

44
Q

0.140 moles of a gas has a volume of 2.00 dm3 at a pressure of 90.0 kPa. Calculate the temperature of the gas

A

155 K

45
Q

“What volume of oxygen is required to burn the following gases, and what volume of carbon dioxide is produced? 1 dm3 of methane CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l)
“

A

“O2 2 dm3

, CO2 1 dm3”

46
Q

If 4 dm3 of hydrogen sulphide is burned in 10 dm3 of oxygen, what is the final volume of the mixture (give the volume of each gas at the end)? 2 H2S(g) + 3 O2(g) → 2 H2O(g) + 2 SO2(g)

A

4 dm3 O2, 4 dm3 H2O, 4 dm3 SO2, total 12 dm3 gas

47
Q

Calculate the number of moles in the following. 2 dm3 of 0.05 mol dm-3 HCl

A

0.1

48
Q

“Calculate the number of moles in the following. 50 litres of 5 mol dm-3 H2SO4
“

A

250

49
Q

Calculate the number of moles in the following. 10 cm3 of 0.25 mol dm-3 KOH

A

0.0025

50
Q

Calculate the concentration of the following in both mol dm-3 and g dm-3 0.400 moles of HCl in 2.00 litres of solution

A

0.2 mol dm-3 , 7.3 g dm-3

51
Q

Calculate the concentration of the following in both mol dm-3 and g dm-3 12.5 moles of H2SO4 in 5.00 dm3 of solution

A

2.5 mol dm-3 245.3 g dm-3

52
Q

Calculate the concentration of the following in both mol dm-3 and g dm-3 1.05 g of NaOH in 500 cm3 of solution

A

0.0512 mol dm-3 , 2.10 g dm-3

53
Q

25.0 cm3 of a solution of sodium hydroxide required 18.8 cm3 of 0.0500 mol dm-3 H2SO4. H2SO4 + 2 NaOH → Na2SO4 + 2 H2O Find the concentration of the sodium hydroxide solution in mol dm-3

A

0.0752 mol dm-3

54
Q

What volume of 5.00 mol dm-3 HCl is required to neutralise 20.0 kg of CaCO3? 2 HCl + CaCO3 → CaCl2 + H2O + CO2

A

79.9 dm3

55
Q

Limestone is mainly calcium carbonate. A student wanted to find what percentage of some limestone was calcium carbonate. A 1.00 g sample of limestone is allowed to react with 100 cm3 of 0.200 mol dm-3 HCl. The excess acid required 24.8 cm3 of 0.100 mol dm-3 NaOH solution in a back titration. Calculate the percentage of calcium carbonate in the limestone. CaCO3 + 2 HCl → CaCl2 + H2O + CO2, HCl + NaOH → NaCl + H2O

A

87.70%

56
Q

An impure sample of barium hydroxide of mass 1.6524 g was allowed to react with 100 cm3 of 0.200 mol dm-3 hydrochloric acid. When the excess acid was titrated against 0.228 mol dm-3 sodium hydroxide in a back titration, 10.9 cm3 of sodium hydroxide solution was required. Calculate the percentage purity of the sample of barium hydroxide. Ba(OH)2 + 2 HCl → BaCl2 + 2 H2O, HCl + NaOH → NaCl + H2O

A

90.80%

57
Q

Write the empirical formula of each of the following substances. a) C2H6 b) P2O3 c) SO2 d) C6H12

A

a CH3 b P2O3 c SO2 d CH2

58
Q

” The empirical formula and relative molecular mass of some simple molecular compounds are shown below. Work out the molecular formula of each one. b) C2H5 Mr = 58 c) CH2 Mr = 70 e) CH Mr = 78 f) CH2 Mr = 42
“

A

b) C4H10 c) C5H10 e) C6H6 f C3H6

59
Q

50.0 g of a compound contains 22.4 g of potassium, 9.2 g of sulphur, and the rest oxygen. Calculate the empirical formula of the compound.

A

K2SO4

60
Q

A compound contains 40.0 g of carbon, 6.7 g of hydrogen and 53.5 g of oxygen. It has a relative molecular formula of 60. Find both the empirical and the molecular formula of the compound.

A

CH2O, C2H4O2

61
Q

A compound contains 59.4% carbon, 10.9% hydrogen, 13.9% nitrogen and 15.8% oxygen, by mass. Find the empirical formula of the compound.

A

C5H11NO

62
Q

25.0 cm3 of 0.0400 mol dm-3 sodium hydroxide solution reacted with 20.75 cm3 of sulphuric acid in a titration. Find the concentration of the sulphuric acid.

A

0.0241 mol dm-3

Chemistry (21 decks)

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