Quantative chemistry

Question 1

What does the law of conservation of mass state?

Answer 1

no atoms are lost or made during a chemical reaction so the mass of products equals the mass of the reactants

Question 2

How do you calculate the relative formula made of a compound?

Answer 2

adding up the relative atomic masses of all the atoms present

Question 3

I’m a balanced chemical equation what does the sun of the relative formula masses of the reactants in the quarries shown equal?

Answer 3

the sun of the relative formula masses of the products in the quantities shown

Question 4

What are some examples of reactions that appear to involve a change in mass?

Answer 4

gases lost or gained from the atmosphere

Question 5

What is meant by measurement uncertainty?

Answer 5

the margin of doubt that exists for the result of any measurement

Question 6

What are chemical amours measured in and what is the unit?

Answer 6

moles (mol)

Question 7

what is the number of atoms, molecules or ions in a mole of a given substance?

Answer 7

Avogadro constant

Question 8

What is the mass of one mole of a substance in grams equal to?

Answer 8

it’s relative formula mass

Question 9

How do you calculate the masses of substances shown in a balanced symbol equation?

Answer 9

mr mr table

Question 10

How do you calculate the masses of reactants and products from the balance symbol equation and the mass of a given reactant or product?

Answer 10

mr mr table

Question 11

How do you balancing equation?

Answer 11

using a table

Question 12

What does it mean if a reactant is the limiting reactant?

Answer 12

the reactant that get consumed first in a chemical reaction and therefore limits how much product can be formed

Question 13

What does it mean if a reactant is in excess?

Answer 13

a substance that is not wholly consumed or entirely reacted

Question 14

What can the concentration of a solution be measured in?

Answer 14

Mass given volume of solution (g/dm3)

Question 15

How is the mass of a solute and the volume of a solution related to the concentration of the solution?

Answer 15

concentration can be increased by dissolving more solute in a given volume of solution. this then increases the mass of the solute.

Question 16

Why is it not always possible to obtain the calculated amount of product from reaction?

Answer 16

the reaction may not go to completion because it is reversible or some product may be lost

Question 17

What is the amount of product obtained known as?

Answer 17

Yield

Question 18

What is percentage yield?

Answer 18

how much product is obtained compared to the maximum possible mass

Question 19

How do you calculate the percentage yield of a product from the actual yield of a reaction?

Answer 19

actual yield divided by theoretical yield x 100

Question 20

What is the atom economy?

Answer 20

Measure of the amount of starting materials to end up as useful products

Question 21

Why is atom economy important?

Answer 21

a reaction with high atom economy is important for sustainability because it uses fewer natural resources and produces less waste

Question 22

How do you calculate the atom economy of a reaction?

Answer 22

total mr of desired product/ total mr of all products x100

Question 23

What is concentrate measured in?

Answer 23

mol/dm3

Question 24

How do you calculate the amount of moles of solute or the mass in grams of salt in a given volume?

Answer 24

Mass/volume

Question 25

What is the volume of one mole of any gas at room temperature and pressure?

Answer 25

24dm3

Question 26

What can the volumes of gaseous reactants and products be calculator from?

Answer 26

Balanced equation for the reaction

Question 27

How do you calculate the volume of a gas at room temperature?

Answer 27

moles/volume