Quantitative Chemistry (3)

Question 1

What is the Atomic Mass (Ar)

Answer 1

• The mas number, this can be seen on the periodic table

Question 2

How do you calculate the %mass of an element in a compound

Answer 2

Ar x number of atoms of that element / Mr of the compound x 100

Question 3

What is the Relative Formula Mass (Mr)

Answer 3

• the relative atomic mass of all the atoms in a compound added together

Question 4

What is Avogadro Constant

Answer 4

6.02 x 10 to the power of 23

Question 5

What is one mole of any substance

Answer 5

• one mole of atoms or molecules of any substance will have a mass in grams equal to the relative formula mass (Ar or Mr) for that substance
• Carbon has a Ar of 12, so one mole of carbon weighs exactly 12g

Question 6

What is the formula for number of moles

Answer 6

Mass in grams / Mr

Question 7

What is the conservation of mass

Answer 7

• No atoms or destroyed or created in a reaction (same number of atoms on each side of the equation)

Question 8

Why could there be a change in mass in a reaction

Answer 8

• if the mass increases one of the reactants is a gas found in the air and all the products are solids, liquids or aqueous
• if the mass decreases one of the products is a gas and all the reactants are solids, liquids or aqueous

Question 9

What are the terms for limiting reactants

Answer 9

• the reactant that is all used up is called the limiting reactant
• the reactant that is left over is described as being in excess

Question 10

What is the volume of a gas

Answer 10

Mass of gas / Mr of gas x24

Question 11

What is conc in g/dm cubed

Answer 11

mass/volume

Question 12

what is conc in mol/dm cubed

Answer 12

number of moles / volume