Analysis by Mass

1
Analysis by Mass

• Chapter 2

2
Unit 3

• Consists of Area of Study 1
• Chemical analysis
• Area of Study 2
• Organic Chemical Pathways
• Each area of study will take about a term
• Though hopefully quicker
• There are 3 sacs and 1 exam a semester

3
The Exam

• This is what you are working towards.
• The chemistry unit 3 exam is on June 10th
• It consists of 15 minutes reading time and 1.5
  hours writing time.
• It is made up of 20 multiple choice questions and
  about 8 short answer questions
• You get a data booklet and are allowed a
  scientific calculator (no graphics)

4
The S.A.C.s

• There are 3 S.A.C.s in unit 3
• The first one is in Area of Study 1
• This is the extended experimental investigation
  (E.E.I.)
• This will begin in week 6 (Mar 9) and will take
  about 3 weeks.
• It consists of 3 practical activities, questions
  to be answered on each prac, risk assessments to
  be written for each prac, a report to be written
  on all 3 pracs.
• The E.E.I. will be on the analysis of the
  composition of lawn fertiliser

5
The S.A.C.s

• The next two S.A.C.s will be in area of study 2.
• One will be a practical report
• One will be a response to written stimulus

6
Significant Figures

• All your answers to calculations this year must
  be to significant figures.
• Look at page 470 (Appendix 1)
• A zero that comes before integers in not
  significant but a zero that comes after an
  integer is.
• Significant figures is where your final value you
  calculate is only as precise as your least
  precise piece of data.
• Meaning your answer has to use the lowest amount
  of significant figures that the question contains.

7
So lets review the holiday homework

• What is the difference between qualitiative and
  quantitative analysis?
• What are some analysis techniques and why might
  we use them?
• Look at page 12 worked example and answer
  question 1 on page 12.
• Remember by mass is
• Do questions 3 and 5 page 12

8
Empirical Formula

• Simplest whole number ratio of the atoms present
  in the compound

Step 1 Measure the mass (m) of each element in
the compound
Step 2 Calculate the amount in mole (n) of each
element in the compound
Step 3 Calculate the simplest whole number ratio
of moles of each element in the compound
Step 4 Determine the empirical formula of the
compound
9
Molecular Formula

• Gives the actual number of atoms of each element
  present in a molecule of compound
• One unit can be the empirical formula molecular
  mass

10
Stoichiometry

• What equations do we know??
• Page 21
• Lets do question 21 together.

11
Homework

• P.12 Q 1, 3, 5
• P.25 Q 21, 25, 27, 29, 31
• P. 26 Q 36, 41, 42, 44