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Chimpo Chemistry IB > 1.4 Counting Particles by Mass: The Mole > Flashcards

1.4 Counting Particles by Mass: The Mole Flashcards

1
Q

The total number of ions in one mole of NaCl is…

(Avogadro’s constant = 6.02 x 1023)

A

The total number of ions in one mole of NaCl is:

2 x 6.02 x 1023 = 1.204 x 1024

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2
Q

True or False?

There are 6.02 x 1023 carbon dioxide molecules in one mole of carbon dioxide.

A

True.

There are 6.02 x 1023 carbon dioxide molecules in one mole of carbon dioxide.

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3
Q

What is the SI unit for amount of substance?

A

A mole is the SI unit of amount of substance.

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4
Q

What is the Avogadro constant?

A

The Avogadro Constant is 6.02 x 1023, which is the number of particles in one mole of a substance.

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5
Q

True or False?

One mole of any substance contains the same number of particles.

A

True.

One mole of any substance contains the same number of particles.

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6
Q

What does molar mass mean?

A

Molar mass is the mass of 1 mole of a substance, containing 6.02 x 1023 particles.

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7
Q

How many of the following does 4 moles of hydrogen gas contain?

Atoms

Molecules

A

4 moles of hydrogen gas contains:

Atoms = 4 x 2 x 6.02 x 1023 = 48.16 x 1023.

Molecules = 4 x 6.02 x 1023 = 24.08 x 1023.

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8
Q

Define the term relative atomic mass.

A

Relative atomic mass is the weighted average mass of one atom compared to one-twelfth the mass of a carbon-12 atom.

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9
Q

How is relative molecular mass, Mr, calculated for compounds?

A

Relative molecular mass, Mr, is calculated by summing the relative atomic masses of all atoms in the molecule.

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10
Q

True or False?

The relative atomic mass has units.

A

False.

The relative atomic mass has no units as it is a ratio and the units cancel each other out.

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11
Q

What is the difference between relative molecular mass and relative formula mass?

A

Relative molecular mass is used for molecules, while relative formula mass is used for compounds containing ions. They are calculated in the same way.

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12
Q

State the equation for calculating the number of particles in terms of moles.

A

The equation for calculating the number of particles in terms of moles is:

Number of particles = number of moles × Avogadro constant

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13
Q

What is the relative formula mass of CuCO3?

A

The relative formula mass of CuCO3 is:

63.5 + 12 + (16 x 3) = 123.5

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14
Q

What is the relative molecular mass of C5H5N?

A

The relative molecular mass of C5H5N is:

(12 x 5) + (1 x 5) + 14 = 79

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15
Q

What is the relative molecular mass of NH4NO3?

A

The relative molecular mass of NH4NO3 is:

14 + (1 x 4) + 14 + (16 x 3) = 80

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16
Q

True or False?

The relative formula mass of CaCO3 is 100. (Ca=40, C=12, O=16)

A

True.

The relative formula mass of CaCO3 is = 40+12 + (16 x 3) = 100

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17
Q

Using moles, mass in grams and the molar mass, complete the equation:

Moles =

A

Using moles, mass in grams and the molar mass, the equation is:

Moles = mass / molar mass

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18
Q

State the equation for molar mass using moles and mass.

A

The equation for molar mass using moles and mass is:

molar mass = mass / moles

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19
Q

How many moles are in 45.0 g of water?

Mr H2O = 18.0

A

To calculate the number of moles:

Moles = mass / molar mass

Moles = 45.0 / 18.0

Moles = 2.5

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20
Q

Calculate the mass of 0.25 moles of copper carbonate, CuCO3.

Mr CuCO3 = 123.5

A

To calculate the mass:

Mass = moles x molar mass

Mass = 0.25 x 123.5

Mass = 30.9 (or 30.875) g

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21
Q

0.5 moles of a compound has a mass of 22.0 g.

Calculate the molar mass, in g mol-1, of the compound.

A

To calculate the molar mass:

Molar mass = mass / moles

Molar mass = 22.0 / 0.5

Molar mass = 44.0 g mol-1

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22
Q

How do you calculate the molar mass of a compound for a moles, mass, molar mass calculation?

A

To calculate the molar mass of a compound for a moles, mass, molar mass calculation, you add the atomic masses of all the atoms in the compound.

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23
Q

Complete the equation connecting moles, mass and molar mass.

Mass =

A

The equation connecting moles, mass and molar mass is:

mass = moles x molar mass

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24
Q

How many hydrogen atoms are in 0.020 moles of CH3CHO?

A

There are 4 H atoms in 1 molecule of CH3CHO

So, there are 0.080 moles of H atoms in 0.020 moles of CH3CHO

The number of H atoms is the amount in moles x L

This comes to 0.080 x (6.02 x 1023) = 4.8 x 1022 atoms

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25
How many moles of hydrogen atoms are in 1.806 x 1023 molecules of H2O2?
In 1.806 x 1023 molecules of H2O2 there are 2 x (1.806 x 1023) atoms of H So, there are 3.612 x 1023 atoms of H The number of moles of H atoms is the number of particles ÷ L This comes to 3.612 x 1023 ÷ (6.02 x 1023) = 0.60 moles of H atoms
26
What is the difference between empirical and molecular formula?
The molecular formula shows the actual number of atoms of each element in a molecule, while the empirical formula shows the simplest ratio.
27
State the steps to calculate an empirical formula.
The steps to calculate an empirical formula are: 1 Write the element 2 Write the value for each element 3 Write the relative atomic mass 4 Calculate moles 5 Calculate ratio 6 Write final formula.
28
Define molecular formula.
The molecular formula gives the actual numbers of atoms of each element present in one molecule of a compound.
29
How do you calculate the molecular formula from the empirical formula?
To calculate the molecular formula from the empirical formula, multiply the subscripts in the empirical formula by n, where n = (molecular mass / empirical formula mass).
30
True or False? If the molecular formula of benzene is C6H6 the empirical formula is CH.
True. If the molecular formula of benzene is C6H6 the empirical formula of benzene is CH.
31
What is a hydrated salt?
A hydrated salt is a crystallised salt that contains water molecules as part of its structure.
32
True or False? The empirical formula is correctly calculated to be CH.
TRUE The empirical formula is CH.
33
What mistake is made in the following empirical formula calculation? The empirical formula is correctly calculated to be Mg2Cl.
The mistake in the empirical formula calculation is that the mole calculations are incorrect / upside down. The correct calculation is: The empirical formula is correctly calculated to be MgCl2.
34
What mistake is made in the following empirical formula calculation? The empirical formula is correctly calculated to be C2H3
The mistake in the empirical formula calculation is that the mole calculations are incorrect / upside down. The correct calculation is: So, the empirical formula is CH3.
35
The empirical formula of a compound is CH3. The molar mass of the compound is 30 g mol-1. What is the molecular formula of the compound?
The mass of the empirical formula, CH3, is 12 + (1 x 3) = 15. 30 / 15 = 2, which means that two lots of the empirical formula are needed. So, the molecular formula is C2H6.
36
What information from the Periodic Table is required to calculate the empirical formula of a metal oxide?
The information from the Periodic Table that is required to calculate the empirical formula of a metal oxide is: The atomic mass of the metal The atomic mass of oxygen
37
What is the equation to calculate the percentage composition by mass of an element in a compound?
The equation for the percentage by mass of an element is: Total Ar of element / Total Mr of the compound x 100
38
True or False? The percentage composition of elements in a compound always adds up to 100%.
True. The percentage composition of elements in a compound always adds up to 100%.
39
What is the percentage composition by mass of hydrogen in water (H2O)? Ar (H) = 1, Ar (O) = 16
The percentage composition by mass of hydrogen in water (H2O) is: (2 / 18) x 100 = 11.1 %.
40
True or False? The percentage composition of oxygen in carbon dioxide, CO2, is: (16 / 44) x 100 = 36.4 % Ar (C) = 12, Ar (O) = 16, Mr (CO2) = 44
False. The percentage composition of oxygen in carbon dioxide, CO2, is: (32 / 44) x 100 = 72.7 % This is because CO2 contains 2 oxygen atoms.
41
True or False? The percentage composition by mass of Mg in MgO is 50%.
False. Ar (Mg) = 24 Ar (O) = 16 Mr (MgO) = 40 So, the percentage by mass of Mg in MgO is 24 / 40 x 100 = 60%.
42
True or False? The mass of nitrogen in ammonium nitrate, NH4NO3, is 28.
True. The mass of nitrogen in ammonium nitrate, NH4NO3, is 28 because there are two nitrogen atoms in the compound.
43
What is the percentage of fluorine in tin(II) fluoride, SnF2? Ar (Sn) = 119, Ar (F) = 19
The percentage of fluorine in tin(II) fluoride, SnF2 is: Mass of fluorine = 2 x 19 = 38 Mass of tin(II) fluoride = 119 + (2 x 19) = 157 Percentage of fluorine = 38 / 157 x 100 = 24.2%.
44
Using moles, volume in dm3 and concentration, complete the equation: Moles =
Using moles, volume in dm3 and concentration, the equation is: Moles = concentration x volume
45
Calculate the number of moles of solute present in 2.0 dm3 of a solution whose concentration is 0.15 mol dm-3.
To calculate the number of moles of solute present in 2.0 dm3 of a solution whose concentration is 0.15 mol dm-3: Moles = concentration x volume Moles = 0.15 x 2.0 = 0.3 moles
46
What are the two common units for concentration?
The two common units for concentration are: g / dm3 mol / dm3
47
State the equation for concentration using moles and volume.
The equation for concentration using moles and volume is: concentration = moles / volume
48
What is the concentration of a solution where 1.0 mole of solute is dissolved in 2.0 dm3 of water?
The concentration of a solution where 1.0 mole of solute is dissolved in 2.0 dm3 of water is: Concentration = moles / volume Concentration = 1.0 / 2.0 = 0.5 mol dm-3
49
How do you calculate the volume of a solution using moles and concentration?
The equation to calculate the volume of a solution using moles and concentration is: Volume = moles / concentration
50
Using volume in dm3 and concentration, complete the equation: Moles =
Using moles, volume in dm3 and concentration, the equation is: Moles = concentration x volume
51
Calculate the number of moles in 2.5 dm3 of a solution that has a concentration of 0.30 mol dm-3.
To calculate the number of moles present in 2.5 dm3 of a solution which has a concentration of 0.30 mol dm-3: Moles = concentration x volume Moles = 0.30 x 2.5 = 0.75 moles
52
What is 27.50 cm3 in dm3?
27.50 cm3 is 0.0275 dm3.
53
A solution of HCl has a volume of 23.55 cm3 and contains 0.00375 moles. What is its concentration in mol dm-3?
The concentration in mol/dm3 of a solution of HCl with a volume of 23.55 cm3 and contains 0.00375 moles is: Volume in dm3 = 0.02355 dm3 Concentration = 0.00375 / 0.02355 = 0.16 mol/dm3
54
What are the four steps to solve a titration calculation?
The four steps in a titration calculation are: 1 Write out the balanced equation for the reaction 2 Calculate the moles of the known solution given the volume and concentration 3 Use the equation to deduce the moles of the unknown solution 4 Use the moles and volume of the unknown solution to calculate the concentration
55
Using moles and volume in dm3, complete the equation: Concentration =
Using moles, volume in dm3 the equation is: Concentration = moles / volume
56
What is 0.03905 dm3 in cm3?
0.03905 dm3 is 39.05 cm3.
57
Explain how many moles of HCl will be neutralised by 0.05 moles of NaOH. HCl + NaOH → NaCl + H2O
0.05 moles of HCl would be required as this reaction is a 1:1 ratio.
58
True or False? 1 ppm is equivalent to 1 mg in 1 kg.
True. 1 ppm is equivalent to 1 mg in 1 kg.
59
How do you convert concentration from g dm-3 to mol dm-3?
To convert concentration from g dm-3 to mol dm-3, you multiply by the molar mass: concentration (g dm-3) = concentration (mol dm-3) × molar mass (g mol-1)
60
True or False? Avogadro’s Law states that equal amounts of gases occupy the same volume of space at the same temperature and pressure.
True. Avogadro’s Law states that equal amounts of gases occupy the same volume of space at the same temperature and pressure.
61
How many moles of gas are in 45.4 dm3 at STP?
There are 2 moles of gas in 45.4 dm3. moles = v o l u m e (dm3) / 22.7 = 45.4 / 22.7 = 2
62
What volume would 2.5 moles of a gas occupy at STP?
2.5 moles of gas will occupy 56.75dm3 at RTP. volume (dm3) = moles x 22.7 volume (dm3) = 2.5 x 22.7 = 56.75dm3
63
What volume of ammonia is produced from 600 cm3 of hydrogen? N2 (g) + 3H2 (g) rightwards harpoon over leftwards harpoon 2NH3 (g)
The volume of ammonia is produced from 600 cm3 of hydrogen is 400 cm3. N2 (g) + 3H2 (g) rightwards harpoon over leftwards harpoon 2NH3 (g) hydrogen : ammonia = 3:2 ratio volume of ammonia = 600 cm3 x 2/3 = 400 cm3
64
250 cm3 of oxygen gas reacts with propane. Calculate the volume, in cm3, of carbon dioxide produced. C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g)
If 250 cm3 of oxygen gas reacted reacted with propane, 150 cm3 of carbon dioxide is formed. C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g) oxygen : carbon dioxide = 5:3 ratio volume of carbon dioxide = 250 cm3 x 3 / 5 = 150 cm3
65
Calculate the volume, in cm3, of propane required to react with 500 cm3 oxygen. C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g)
100 cm3 of propane was required to react with 500 cm3 oxygen. C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g) propane : oxygen = 1:5 ratio volume of propane = 500 / 5= 100 cm3
66
State the change in the number of gaseous moles for this reaction. 4NH3 (g) + 5O2 (g) → 4NO (g) + 6H2O (l)
The change in the number of moles of gas is 9 to 4 OR decreases by 5. 4NH3 (g) + 5O2 (g) → 4NO (g) + 6H2O (l)
67
What is the volume of one mole of any gas at STP?
At standard temperature and pressure (STP), one mole of any gas has a volume of 22.7 dm3.
68
Define the term standard temperature and pressure, STP.
Standard temperature and pressure, STP, refers to a temperature of 0°C (273 K) and a pressure of 100 kPa.
69
True or False? Avogadro's Law applies only to ideal gases
True. Avogadro's Law applies only to ideal gases.
70
True or False? The volume of a gas is directly proportional to the number of moles at constant temperature and pressure.
True. The volume of a gas is directly proportional to the number of moles at constant temperature and pressure.

Chimpo Chemistry IB (6 decks)

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