Quantitative Chemistry

Question 1

What is the law of conservation of mass ?

Answer 1

No atoms are lost or made during a chemical reaction so the mass of the products equal the mass of reactants

Question 2

What are reactants ?

What are products ?

Answer 2

The starting materials are the reactants.The chemicals formed in a reaction are called products.

Question 3

Ionic compounds
What are ions ?
What do metals form?
What do non metals form ?

Answer 3

Ionic compounds are formed when metals react with non metals .
Ions are atoms with a charge .
Metals form positive ions . Non metals negative ions.

Question 4

An important fact about transition metals

Answer 4

Transition metals can form negative ions .

Question 5

What is a key rule for the formula in an ionic compound ?

So…

Answer 5

In an ionic compound the charges on the ions have to cancel out to leave an overall charge of 0.
So no ionic compounds have an overall charge .

Question 6

Why can’t you change the small number in chemical formula ?

Answer 6

You are never allowed to change the small numbers in a chemical formula as this produces a different molecule .

Question 7

What is relative formula mass ?
What units does relative formula mass have ?
What does relative formula mass include ?

Answer 7

The relative formula mass of a compound is the sum of the relative atomic masses of the atom.
Relative formula mass has no units
Relative formula mass never included big numbers

Question 8

What does a mole mean ?
Eg:
What does this mean?

Answer 8

A very large number
Eg:16g of oxygen =1 mole of oxygen atoms.
The atomic mass of any element then we’ve got one mole of grams of that element .

Question 9

Why is a mole useful ?

What is the equation for mole ?

Answer 9

The mole is very useful because it always scientists to calculate how many atoms of substance they have in a chemical reaction

                                       Mass(g) Number of moles =\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
                               Relative atomic mass

Question 10

What equation do you use to calculate the moles of a compound ?

Answer 10

Number of moles = mass(g)
_________________
Relative formula mass

Question 11

What is avogadro’s constant ?

Answer 11

23

6.02 x 10

Question 12

What do we do to the chemical reaction to make it practical and convenient ?

Answer 12

We need to make one of the reactants more than the other reactants .

Question 13

What do we call the reactant that’s fully used up called ?

Answer 13

Limiting reactant

Question 14

What do we call the reactant that’s not used up called?

Answer 14

Excess reactant

Question 15

What does concentration tells us ?
What is a solute ?
What is a solvent ?

Answer 15

Concentration tells us the mass of a solute in a given volume of solution.
A solute is a chemical that’s dissolved in
a solvent
In chemistry water is often used a solvent j in

Question 16

What is the unit for concentration ?

What equation do we use to calculate concentration ?

Answer 16

3
Units = (g/dm )
Mass(g)
Concentration = _________________
3 Volume (dm cubed)
(g/dm )

Question 17

What happens if you increase the mass of the solute and keep the volume the same ?

Answer 17

What happens if you increase the mass of the solute and keep the volume the same , then we increase the concentration .

Question 18

What happens if you increase the volume of the solution and keep the mass of the solute the same ?

Answer 18

What happens if you increase the volume of the solution and keep the mass of the solute the same , then we decrease the concentration