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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
What is the atom economy to make tungsten in this reaction: WO3 + 3H2 → W + 3H2O
77.30%
26
"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"
5.10g
27
At 273 K and 101000 Pa, 6.319 g of a gas occupies 2.00 dm3 . Calculate the relative molecular mass of the gas.
71
28
Calculate the atom economy when titanium is extracted from titanium chloride. TiCl4 + 2Mg → Ti + 2MgCl2
20.10%
29
What standard units are used for concentration of a solution?
mol/dm3
30
How are cm³ converted to dm³?
Divide by 1000
31
What are concordant titres?
Titres within 0.1cm³ of each other
32
What colour is phenolphthalein in acid and alkali?
Colourless in acid, purple in alkali
33
State the ideal gas equation
PV = nRT
34
What is the empirical formula of a substance?
The formula that represents the simplest whole number ratio of the atoms of each element present in the compound.
35
What is the molecular formula?
The actual number of atoms of each element in one molecule of a compound
36
What is an ionic equation?
A simplified equation showing the ions present in a reaction
37
What is a spectator ion?
An ion that does not take part in a reaction
38
Which substances produce ions in ionic equations?
Aqueous solutions of ionic compounds
39
"Write an ionic equation, including state symbols, for the reaction of aqueous ammonia with hydrochloric acid "
H+(aq) + NH3(aq) → NH4+(aq)
40
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
Pb2+(aq) + 2Br–(aq) → PbBr2(s)
41
"Write an ionic equation, including state symbols, for the reaction of potassim carbonate solution with nitric acid "
H+(aq) + CO32-(aq) → H2O + CO2(g)
42
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
Pb2+(aq) + 2Br–(aq) → PbBr2(s)
43
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
4.53 m3
44
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
155 K
45
"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) "
"O2 2 dm3 | , CO2 1 dm3"
46
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)
4 dm3 O2, 4 dm3 H2O, 4 dm3 SO2, total 12 dm3 gas
47
Calculate the number of moles in the following. 2 dm3 of 0.05 mol dm-3 HCl
0.1
48
"Calculate the number of moles in the following. 50 litres of 5 mol dm-3 H2SO4 "
250
49
Calculate the number of moles in the following. 10 cm3 of 0.25 mol dm-3 KOH
0.0025
50
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
0.2 mol dm-3 , 7.3 g dm-3
51
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
2.5 mol dm-3 245.3 g dm-3
52
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
0.0512 mol dm-3 , 2.10 g dm-3
53
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
0.0752 mol dm-3
54
What volume of 5.00 mol dm-3 HCl is required to neutralise 20.0 kg of CaCO3? 2 HCl + CaCO3 → CaCl2 + H2O + CO2
79.9 dm3
55
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
87.70%
56
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
90.80%
57
Write the empirical formula of each of the following substances. a) C2H6 b) P2O3 c) SO2 d) C6H12
a CH3 b P2O3 c SO2 d CH2
58
" 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 "
b) C4H10 c) C5H10 e) C6H6 f C3H6
59
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.
K2SO4
60
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.
CH2O, C2H4O2
61
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.
C5H11NO
62
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.
0.0241 mol dm-3

Chemistry (21 decks)

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