Unit 1-Reaction Quantities Flashcards

1
Q

What is meant by the gram formula mass (GFM) of a substance?

A

The GFM is the mass of one mole of a substance.

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2
Q

How do you calculate the Gram Formula Mass (GFM) of a compound?

A

Work out the formula then add all the mass numbers together.

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3
Q

What is the GFM of Carbon Dioxide?

A

CO2

12 + (2x16) = 44

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4
Q

To calculate the mass of a number of moles, or calculate the number of moles in a certain mass, a formula triangle can be used.

Describe it.

A
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5
Q

How many moles are present in 25 g of calcium carbonate? (GFM=100)

A

number of moles = mass/GFM

25/100 = 0.25 moles

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6
Q

Calculate the mass of 0.25 moles of butane (C4H10)

RAM of Carbon = 12

RAM of Hydrogen = 1

A

mass = number of moles x GFM

mass = 0.25 x 58

mass = 14.5g

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7
Q

If the number of moles of solute and the volume of solvent used is known, the concentration of the solution can be calculated.

Describe the formula triangle.

A
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8
Q

How many of moles in 400cm3 of 0.2 mol l-1 sodium hydroxide (NaOH) solution.

A

Number of moles = concentration x volume

Convert volume to litres by dividing by 1000

= 0.2 x 0.4

= 0.08 moles

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9
Q

Calculate the concentration of the solution formed when 0.75 moles of sodium chloride are dissolved in 500 cm3 of water.

A

Concentration = number of moles/volume.

Convert volume into litres by dividing by 1000.

Concentration = 0.75/0.5

Concentration = 1.5 mol l-1

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10
Q

Calculate the volume of sodium hydroxide used in 0.6 mol l-1 solution containing 1.2 mol of solute.

A

Volume = number of moles / concentration

= 1.2 / 0.6

= 2 litres

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11
Q

Equations can be described as being balanced. What does this mean?

A

A chemical equation is said to be balanced when there are the same number of the same type of every atom on both sides of the equation.

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12
Q

How can you balance an equation?

A

Balancing is adding BIG numbers. You cannot change any of the small numbers in a chemical formula. If balancing is required, put the number in front of the substance.

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13
Q

How would this equation be balanced?

Cu + O2→ CuO

A

2Cu + O2 →​ 2CuO

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14
Q

Balance this equation

C4H8 + O2 → CO2 + H2O

A

Balance Carbons

C4H8 + O2 4CO2 + H2O

Balance Hydrogens

C4H8 + O2 4CO2 + 4H2O

Balance Oxygens

C4H8 + 6O2 4CO2 + 4H2O

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