1. Empirical Formula

2. Objectives To be able to calculate the empirical formula.
To be able to balance equations.
To be able to use equations to calculate the mass of reactants and products.

3. Remember What is the Relative Atomic Mass of Sodium?
What is the Relative Formula Mass of Sodium Chloride?

4. Remember What is the Relative Atomic Mass of Sodium? Answer: 23
What is the Relative Formula Mass of Sodium Chloride?
Answer: = 58.5

5. Empirical Formula
If we know the percentage composition of a compound we can work out the ratio of the numbers of atoms in the compound.
This is called the Empirical Formula.

6. Example
If 9g of aluminium reacts with 35.5g of chlorine, what is the empirical formula of the compound formed?
Step 1: What is the ratio of atoms?
9/27 = 0.3 moles of aluminium atoms
35.5/35.5 = 1 mole of chlorine atoms

7. Finally So: 0.3 moles of aluminium atoms 1 mole of chlorine atoms
Therefore, we need 3 Cl for every 1 Al.
So, formula is AlCl3

8. Try these…
A compound contains 16g of sulfur and 24g of oxygen. What is its empirical formula? (Ar Values: S = 32, O = 16)
A compound contains 44.8g of iron and 19.2g of oxygen. What is its empirical formula? (Ar Values: Fe = 56, O = 16)

9. A compound contains 16g of sulfur and 24g of oxygen
A compound contains 16g of sulfur and 24g of oxygen. What is its empirical formula? (Ar Values: S = 32, O = 16)
Step 1: What is the ratio of atoms?
16/32 = 0.5 moles of sulfur atoms
24/16 = 1.5 mole of chlorine atoms
So 1 S needs 2 Cl, so formula is SCl2

10. Try this one….
A compound contains 44.8g of iron and 19.2g of oxygen. What is its empirical formula? (Masses: Fe = 56, O = 16)

11. A compound contains 44. 8g of iron and 19. 2g of oxygen
A compound contains 44.8g of iron and 19.2g of oxygen. What is its empirical formula? (Masses: Fe = 56, O = 16)
Step 1: What is the ratio of atoms?
44.8/56 = 0.8 moles of iron atoms
19.2/16 = 1.2 mole of oxygen atoms
So 2 Fe needs 3 O, so formula is Fe2O3

12. Step 1: What is the ratio of atoms?
44.8/56 = 0.8 moles of iron atoms
19.2/16 = 1.2 mole of oxygen atoms
If you multiply by 10, you get 8 Fe to 12 O
If you divide by 4, you get 2 Fe to 3 O.
So 2 Fe needs 3 O, so formula is Fe2O3

13. Can you balance this equation?
Balancing
Hydrogen reacts with oxygen to produce water.
H O2  H20
Can you balance this equation? 2 2

14. Using equations
2H O2  2H20
This means that 2 moles of Hydrogen reacts with 1 mole of oxygen.
This reaction produced 2 moles of water.

15. Using equations
2H O2  2H20
Ar of H = 1, so mass of 1 mole of H2 = 2 x 1 = 2g. Equation tells us we have 2 moles so we need 4g.
Ar of O = 16, so mass of 1 mole of O2 = 2 x 16 = 32g. Equation tells us we only need 1 mole so we need 32g.
Mr of H2O = = 18, so mass of 1 mole of H2O = 18g. Equation tells us we produce 2 moles so we produce 32g.

16. 2NaOH + Cl2  NaOCl + NaCl + H20
Using equations
2NaOH + Cl2  NaOCl + NaCl + H20
If we have a solution containing 100g of NaOH, how much chlorine gas should we pass through the solution to make bleach (NaOCl)?

17. 2NaOH + Cl2  NaOCl + NaCl + H20
Using equations
2NaOH + Cl2  NaOCl + NaCl + H20
Ar of H = 1
Ar of O = 16
Ar of Na = 23
Ar of Cl = 35.5

18. 2NaOH + Cl2  NaOCl + NaCl + H20
Using equations
2NaOH + Cl2  NaOCl + NaCl + H20
1 mole of NaOH = 23 + !6 + 1 = 40g
1 mole of Cl2 = 35.5 x 2 = 70g
So, 100g of NaOH is 100/40 = 2.5 moles

19. 2NaOH + Cl2  NaOCl + NaCl + H20
Using equations
2NaOH + Cl2  NaOCl + NaCl + H20
Equation states that for every 2 moles of NaOH we need only 1 mole of Chlorine.
So we need 2.5/2 = 1.25 moles of chlorine.
If 1 mole of Chlorine has a mass of 71g, then 1.25 x 71 = 88.75g of chlorine to react with 100g of NaOH.

20. Objectives To be able to calculate the empirical formula.
To be able to balance equations.
To be able to use equations to calculate the mass of reactants and products.

21. Try your best to…
Write down the steps to balancing equations!

22. Hydrates

23. % H2O in a Hydrate
Certain substances have water molecules associated with their structure. Many salts
fall into this category and we refer to them as hydrated salts. Different salts have
different numbers of of water molecules - BaCl2•2H2O; CuSO4•5H2O.
PROBLEM: Calculate the % by mass of water in one mole of BaCl2•2H2O
%H2O = (mass of H2O in one Mol/mass of BaCl2•2H2O) x 100
%H2O = (36 grams/243 grams) x 100 = 14.8% H2O

24. How do you make Rice Krispy Treats?
No really how do you make them? Write down a recipe in the form of a formula!

26. Reaction Types
You should be able to identify the following types of reactions:
Combination or Synthesis Reaction
Decomposition or Analysis Reaction
Single Replacement Reaction
Double Replacement Reaction
Combustion Reactions
Complete
Incomplete

27. Combination (Synthesis)
In a combination reaction usually two elements combine to form a compound.
2Na(s) + Cl2(g) = 2NaCl(s)

28. Combination (Synthesis)
Complete the following combination reactions by balancing them:
N2(g) + H2(g) = NH3(g)
Al(s) + O2(g) = Al2O3(s)
S(s) + O2(g) = SO3(g)

29. Decomposition (Analysis)
More complex compounds breakdown into simpler substances or elements.
CaCO3(s) = CaO(s) + CO2(g)
Notice in this case the equation is already balanced, this will not always be the case.

30. Decomposition (Analysis)
Balance the following decomposition reactions:
HI(g) = H2(g) + I2(g)
N2O5(g) = N2(g) + O2(g)
KClO3(s) = KCl(s) + O2(g)

31. Single Replacement
In a single replacement reaction one of the species in a formula is replaced by another species:
2NaBr(aq) + Cl2(g) = 2NaCl(aq) + Br2(l)
Mg(s) + 2HCl(aq) = MgCl2(aq) + H2(g)
Single replacement
Single replacement

32. Single Replacement Balance the following single replacement reactions:
Cu(s) + AgNO3(aq) = Cu(NO3)2(aq) + Ag(s)
Zn(s) + HCl(aq) = ZnCl2(aq) + H2(g)
Zn(s) + H2SO4(aq) = ZnSO4(aq) + H2(g)

33. AgNO3(aq) + NaCl(aq) = AgCl(s) + NaNO3(aq)
Double Replacement
In a double replacement reaction the species simply exchange places:
AgNO3(aq) + NaCl(aq) = AgCl(s) + NaNO3(aq)
In this case, when we check both sides of the equation we find that there is no need to adjust the coefficients - it is balanced

34. Double Replacement Balance the following double replacement reactions:
Ba(NO3)2(aq) + K2SO4(aq) = BaSO4(s) + KNO3(aq)
Al(NO3)3(aq) + KOH(aq) = Al(OH)3(s) + KNO3(aq)
Cd(NO3)2(aq) + H2S(g) = CdS(s) + HNO3(aq)

35. CH4(g) + 2O2(g) = CO2(g) + 2H2O(g)
Combustion Reactions
Complete combustion generally involves the burning of an organic compound in oxygen to form carbon (IV) oxide and water as products:
CH4(g) + 2O2(g) = CO2(g) + 2H2O(g)

36. 2CH4(g) + 3O2(g) = 2CO(g) + 4H2O(g)
Combustion Reactions
Incomplete combustion reactions generally involve the formation of carbon (II) oxide and water as products:
2CH4(g) + 3O2(g) = 2CO(g) + 4H2O(g)

37. Write a story about all the three types of chemical reactions.
Here are your 2 options
Create a visual representation of 2 of the three chemical reactions! Be creative!
Ie, make a food item, shoes, car,
Write a story about all the three types of chemical reactions.

38. Poster Includes:
Details notes, Important Vocabulary, Create two questions with “twelve words” word stems, with and test question numbers on the test.

39. Seminar Zapata, Oscar Thompson, Rasheed Stewart, Joi
Ramirez-Rodriguez, Lucimar
Lockett, Janell
Cruz, Ariadna
Washington, Naomi
McCain, Franklin
Alston, Eric
Callands, Carlos
Connor, Patrick
Lesane, Virgil
Eliab, Donovan
Brown, Lakelle
Pickard, Jasmine
Stamey, Jania
Javed, Hamzah
Kidd, Christopher
McCall, Brayla
Robinson, Ashleigh
Washington, Naomi
Atchabao, Ibn Khassir
Hopkins, Joshua
Brunson, Joshua
Little, Isaiah
McCain, Franklin
Ramirez, Luis
Santiago Boria, Orangellys
Battle, Rickey
Boyd, Corey
Muhammad-Brown, Infinity
Atchabao, Ibn Khassir

40. 1.1.1 Questions 1-7 1.1.2 Questions 8-12
Test Questions
1.1.1 Questions 1-7
1.1.2 Questions 8-12
1.2.1 Questions 13-19
1.2.2 Questions 20-25