C4: Chemical Calculations

Question 1

What does Ar stand for?

Answer 1

Relative Atomic Mass

Question 2

What does Mr stand for?

Answer 2

Relative Formula Mass

Question 3

What do you times by to get from cm^3 to dm^3?

Answer 3

x1000

Question 4

What are two important rules to remember about relative formula mass?

Answer 4

• Never involves big numbers (co-efficient kind of thing)
• No units

Question 5

What is the relative formula mass?

Answer 5

The RELATIVE FORMULA MASS of a compound is the SUM of the RELATIVE ATOMIC MASS of the atoms in the numbers shown in the formula.

Question 6

What is the RELATIVE ATOMIC MASS?

Answer 6

The RELATIVE ATOMIC MASS of an element is the AVERAGE mass of the ISOTOPE of that element weighted to take into account the ABUNDANCE of each isotope.

Question 7

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Answer 7

Be healthy mate - have a free blue

Question 8

What is the limiting reactant?

Answer 8

The limiting reactant is the reactant that is fully used up

Question 9

What is the excess reactant?

Answer 9

The excess reactant is the reactant that has not been fully used up

Question 10

What is concentration?

Answer 10

Concentration is the MASS of a SOLUTE in a given volume of solution

Question 11

What is a solute?

Answer 11

SOLUTE is a chemical that is DISSOLVED in a SOLVENT

Question 12

What is the common solvent used in chemistry?

Answer 12

Water

Question 13

What is the unit of concentration?

Answer 13

g/dm^3

Question 14

What is the equation for concentration?

Answer 14

Concentration (g/dm^3) = mass (g) / volume (dm^3)

Question 15

When does the concentration increase?

Answer 15

If we INCREASE the MASS of SOLUTE and keep the volume the same, then we INCREASE the CONCENTRATION

Question 16

When does concentration decrease?

Answer 16

If we INCREASE the VOLUME of SOLUTION and keep the mass of the solute the same then we DECREASE the CONCENTRATION