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Chemistry Year 1 > Amount Of Substances > Flashcards

Amount Of Substances Flashcards

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1
Q

What is the definition of a mole?

A

The mole is the amount of substance in grams that has the same number of particles as there are atoms in 12 grams of carbon-12.

This concept is fundamental for chemical calculations.

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2
Q

What is relative atomic mass?

A

The average mass of one atom compared to one twelfth of the mass of one atom of carbon-12.

It is a key concept in understanding the mass of elements.

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3
Q

What is relative molecular mass?

A

The average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12.

This helps in calculating the mass of compounds.

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4
Q

What is the equation for calculating moles for pure solids, liquids, and gases?

A

moles = mass / Mr

Mr is the relative molecular mass.

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5
Q

What is the equation for gases?

A

PV = nRT

Where P is pressure, V is volume, n is moles, R is the gas constant, and T is temperature.

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6
Q

What is the unit of pressure (P) in the gas equation?

A

P is measured in Pascals (Pa).

This is the standard unit for pressure in scientific calculations.

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7
Q

How do you convert temperature from Celsius to Kelvin?

A

Add 273 to the Celsius temperature.

This conversion is essential for gas law calculations.

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8
Q

What is Avogadro’s Number?

A

6.022 × 10^23 atoms in 12 grams of carbon-12.

This number defines the amount of particles in one mole of any substance.

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9
Q

What is the equation for calculating concentration?

A

concentration = moles / volume

This is important for solutions in chemistry.

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10
Q

What are the units of concentration?

A

mol dm^-3 or M.

These units express the amount of substance in a given volume.

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11
Q

How do you convert volumes from cm³ to dm³?

A

Divide by 1000.

This is necessary for unit conversions in volume.

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12
Q

How is molar mass (Mr) calculated for a compound?

A

By adding up the mass numbers of each element in the compound.

Example: For CaCO₃, it’s 40.1 + 12.0 + 16.0 × 3 = 100.1.

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13
Q

What is the equivalent of 1000 mg in grams?

A

1 g.

This conversion is useful for mass calculations.

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14
Q

What is Avogadro’s Constant?

A

6.022 × 10^23 particles per mole

Avogadro’s Constant is the number of atoms, molecules, or ions in one mole of a substance.

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15
Q

Define the mole in relation to carbon-12.

A

The amount of substance in grams that has the same number of particles as 12 grams of carbon-12

The mole is a fundamental concept in chemistry for quantifying substances.

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16
Q

What is the formula to calculate the number of particles in a substance?

A

Number of particles = moles of substance × Avogadro’s constant

This formula applies to any specified entity.

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17
Q

How do you calculate the number of moles from mass and relative atomic mass (Ar)?

A

moles = mass / Ar

This formula is crucial for converting mass to moles in stoichiometric calculations.

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18
Q

What is the formula for density?

A

density = mass / volume

Density is usually expressed in g cm^-3.

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19
Q

True or False: The density of a substance is the same regardless of its state (solid, liquid, gas).

A

False

Density can vary significantly between different states of matter.

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20
Q

How do you calculate the number of molecules in a given mass of a substance?

A

number of molecules = moles × Avogadro’s constant

This is essential for converting moles into actual particle count.

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21
Q

What is an empirical formula?

A

An empirical formula is the simplest ratio of atoms of each element in the compound.

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22
Q

What is the general method to calculate an empirical formula?

A
  1. Divide each mass (or % mass) by the atomic mass of the element.
  2. For each of the answers, divide by the smallest one of those numbers.
  3. Sometimes the numbers calculated will need to be multiplied up to give whole numbers.
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23
Q

What types of data can be used to calculate an empirical formula?

A
  1. Masses of each element in the compound.
  2. Percentage mass of each element in the compound.
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24
Q

What is a molecular formula?

A

A molecular formula is the actual number of atoms of each element in the compound.

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25
Q

How do you determine the molecular formula from the empirical formula?

A

From the relative molecular mass (Mr), work out how many times the mass of the empirical formula fits into the Mr.

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26
Q

How is the molecular ion related to the molecular formula?

A

The molecular ion (the peak with the highest m/z) will be equal to the Mr of the compound.

27
Q

What is a solution?

A

A solution is a mixture formed when a solute dissolves in a solvent. In chemistry, water is most commonly used as the solvent to form aqueous solutions. The solute can be a solid, liquid, or gas.

28
Q

How is molar concentration calculated?

A

Molar concentration is calculated by dividing the amount in moles of the solute by the volume of the solution.

29
Q

What is the unit of molar concentration?

A

The unit of molar concentration is mol dm³, which can also be represented as M.

30
Q

What is the unit of volume?

A

The unit of volume is dm³.

31
Q

How many cm³ are in 1 m³?

A

1 m³ = 1,000,000 cm³.

32
Q

How many dm³ are in 1 m³?

A

1 m³ = 1,000 dm³.

33
Q

How many liters are in 1 dm³?

A

1 dm³ = 1 liter.

34
Q

How many mL are in 1 cm³?

A

1 cm³ = 1 mL.

35
Q

How do you convert cm³ to dm³?

A

To convert cm³ into dm³, divide by 1000.

36
Q

How do you convert m³ to dm³?

A

To convert m³ into dm³, multiply by 1000.

37
Q

What is the formula to calculate moles?

A

moles = mass / Mr.

38
Q

What is mass concentration?

A

The concentration of a solution measured in terms of mass of solute per volume of solution.

mass concentration = mass / volume

39
Q

How do you convert concentration from mol dm³ to g dm³?

A

Multiply the concentration in mol dm³ by the molar mass (Mr) of the substance.

conc in g dm³ = conc in mol dm³ x Mr

40
Q

What is the unit of mass concentration?

A

g dm³

41
Q

What happens when soluble ionic solids dissolve in water?

A

They dissociate into separate ions, leading to differing concentrations of ions compared to the solute.

42
Q

What is the first step in making a solution?

A

Weigh the sample bottle containing the required mass of solid on a 2 dp balance.

43
Q

What should you do after transferring the solid to a beaker?

A

Reweigh the sample bottle and record the difference in mass.

44
Q

How do you ensure the solid dissolves well?

A

Add 100 cm³ of distilled water to the beaker and stir with a glass rod. If necessary, heat gently until all solid dissolves.

45
Q

What is the next step after dissolving the solid in the beaker?

A

Pour the solution into a 250 cm³ graduated flask via a funnel.

46
Q

How do you ensure the solution is uniform?

A

Invert the flask several times after making up to the mark with distilled water.

47
Q

What should you remember when filling the volumetric flask?

A

Fill so the bottom of the meniscus sits on the line on the neck of the flask.

48
Q

What is the ideal gas equation?

A

PV = nRT

49
Q

What does ‘n’ represent in the ideal gas equation?

A

‘n’ represents the total moles of all gases in a mixture.

50
Q

What is the unit of pressure (P) in the ideal gas equation?

A

Pa

51
Q

What is the unit of volume (V) in the ideal gas equation?

A

m³

52
Q

What is the unit of temperature (T) in the ideal gas equation?

A

K

53
Q

What is the value of R in the ideal gas equation?

A

R = 8.31 J K⁻¹ mol⁻¹

54
Q

How do you convert Celsius to Kelvin?

A

Add 273 to the Celsius temperature.

55
Q

What is the formula to calculate moles using the ideal gas equation?

A

moles = PV / RT

56
Q

What is the mass calculation formula in the context of the ideal gas equation?

A

mass = moles x Mr

57
Q

How do you convert 100 kPa to Pa?

A

100 kPa = 100,000 Pa

58
Q

How do you convert 20°C to Kelvin?

A

20°C = 20 + 273 = 293 K

59
Q

How do you convert 500 cm³ to m³?

A

500 cm³ = 0.0005 m³

60
Q

What are potential errors when using a gas syringe?

A

Gas escapes before bung inserted, syringe sticks, some gases are soluble in water.

61
Q

What should be noted when recording gas volume?

A

The temperature and pressure of the room.

62
Q

What is important to include when drawing a gas syringe?

A

Measurement markings on the barrel.

63
Q

Atom economy formula

A
64
Q

Atom yield formulaqq

A

Chemistry Year 1 (16 decks)

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