C4 + 1.2 Chemical Equations Flashcards
What state symbol is used for solids
s
What state symbol is used for gases
g
What state symbol is used for liquids
l
What state symbol is used for aqueous solutions
aq
Match the reactants to the products CH^4 + 2O^2. 2CO^2 + 3H^2O C^2H^5OH + 3O^2. CO^2 C^3H^8 + 5O^2. CO^2 + 2H^2O C + O^2. 3CO^2 + 4H^2O
CH^4 + 2O^2 = CO^2 + 2H^2O
C^2H^5OH + 3O2 = 2CO^2 + 3H^2O
C^3H^8 + 5O^2. = 3CO^2 + 4H^2O
C + O^2. = CO^2
Whats the word equation for water
Hydrogen + oxygen -> water
(Reactants). (Products)
What the symbol equation for water
H^2 (g) + O^2(g) -> H^2O(l) - unbalanced
What do chemical equations show
The reactants (substances you start with) and the products (new substances made) in a reaction
When balancing a chemical equation …
You can NEVER change a chemical formula e.g
H^2(g) +O^2(g) -> H^2O(l) Unbalanced
2H^2(g) + O^2(g) -> 2H^2O(l) Balanced
Why is it important that equations are balanced
Because atoms cannot be created or destroyed in a chemical reaction. This is the law of conservation of mass:
The total mass of products formed in a reaction is equal to the total mass of the reactants
How are the masses of atoms compared
By measuring them relative to atoms of carbon-12
How can you work out the relative formula mass of a compound
By adding up the relative atomic masses (top number on periodic table) of the elements in it, in the ratio shown by it’s formula
e.g h^2SO^4 = (1x2) +32 +(16x4) = 2 + 32 +64 =98
Al^2(SO^4)^3 = (27x2) +(32 x 3) + (16x12) =342
What is a mole
One mole of any substance is its relative formula mass, in grams
What is avogadro constant
The number of atoms, molecules, or ions in a mole. This is always the same: 6.02 x10^23 per mole
How do you calculate moles
Number of moles = mass (g) / Mr (relative atomic mass)
OR rearanged
mass(g) = number of moles x Mr
e.g number of moles in 19.6g of H^2SO^4
= 19.6/98 = 0.20mol.
Mass of 7.5x10^-3 moles of Al^2(SO^4)^3
= (7.5 x 10^-3) x 342 = 2.6g(2sf)
How do you calculate the percentage by mass of each element in a compound
e.g CO^2
Relative formula mass = 12+(2x16)=44
Percentage mass of C in CO^2 = 12/44 x 100 = 27.3%
Add number in front of these compunds to make these equations balanced:
NH^3 + O^2 -> NO + H^2O
HNO^3 -> NO^2 + H^2O + O^2
4NH^3 + 5O^2 -> 4NO + 6H^2O
4HNO^3 -> 4NO^2 + 2H^2O + O^2
What is the reactant that gets used up first in a reaction called?
Limiting reactant. This is the reactant which is NOT in excess
What does the limiting reactant limit
The amount of product formed
What mass of carbon dioxide is formed when 7.41 g of copper(II) carbonate decomposes on heating?
CuCO^3 -> CuO + CO^2
Moles CuCO^3 = 0.060mol
Mass CO^2 = 44x0.060 = 2.64g
Hydrazine (N^2H^4) can be made by reacting ammonia with hydrogen peroxide. What mass of ammonia is needed to make 148g of hydrazine?
Moles N^2H^4 = 4.625 mol
Moles NH^3 = 2x4.625 = 9.25 mol
Mass NH^3 = 17 x 9.26 = 157g
4.8g of Mg (24 Mr) reacting with 7.3 g of HCl (H=1Mr Cl = 35.5 Mr). Which is the limiting reactant
Mg(s) + 2HCl (aq) -> MgCl^2(aq) + H^2(g)
Find moles:
4.8/24 = 0.2mol. 7.3/(1+35.5) = 0.2mol
In reaction it is 2HCl so 0.2 x2 = 0.4 moles are needed.
HCl is the limiting reactant
What is the equivalent measurement of: 1dm 10dm 1dm^2 1dm^3
1dm = 1/10m = 10cm
10dm=1m
1dm^2 =100cm^2
1dm^3 = 1000cm^3
How to you calculate concentration (g/dm^3)
Amount of solute (g) / volume of solution (dm^3)
