quantative chemistry

Question 1

what is the law of conservation of mass

Answer 1

the law of conservation of mass states that no atoms are lost or made during a chemical reaction.
so the mass of the products equals the mass of the reactants

Question 2

write a balanced equation of magnesium reacting with hydrochloric acid

Question 3

define relative atomic mass , and relative formula mass

Answer 3

. ram- average mass of atoms in an element taking into account masses and abundance of its isotopes

. rfm- sum of rams of all atoms in the formula

Question 4

explain why carbon dioxide and water escape from the test tube

Answer 4

they are both gases

Question 5

write down the two formulae that link concentration, mole/mass and volume together

Answer 5

1. concentration (g per dm3)= mass (g) / volume (dm3)
2. concentration (mol per dm3) = nr of moles / volume (dm3)

Question 6

what is the molar volume of gas at room temperature and pressure

Answer 6

1 mole of a gas at room temperature and pressure occupies 24dm3

Question 7

why is it not always possible to obtain the theoritical amount of product in a chemical reaction

Answer 7

. the reaction may not always go to completion because it is reversible.

.some of the product may be lost when it is seperated from the reaction mixture

. some of the reactants may react in ways different to the expected reaction

Question 8

how is the percentage yield of a product in a chemical reaction

Answer 8

percentage yeild=

actual mass of product times 100 / maximum theoritical mass of product