# CHM135H1 Lecture Notes - Iodine Monochloride, Sodium Bicarbonate, Sodium Carbonate

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LECTURE 1 – Chapters 1 & 2

Slide NumberNotes

2- Units matter

3-before SI units, units were body-derived (ie. feet)

-SI units allow for worldwide standardization, so scientists can

communicate without misunderstandings

-One-tenth of a meter is a decimetre

-One-tenth of a decimetre is a centimetre

4- must be comfortable with scientific notation, and able to use it on a

calculator

5- must know how to convert between the multiples

6-(x unit B / y unit A) is the conversation factor

-the equation gets you the measurement in unit B

-the two “unit A”s cancel out

-EX. 24hr(60min/1hr)(2L/1min)(1dm³/1L)

(0.1m/1dm)³(30micrograms/m³) = 86.4 micrograms

-Note that in the above equation, all units cancel out EXCEPT for

micrograms

-Formal solution to EX: Any mass above 86.4 micrograms

violates the standard.

7- Ans: D

8-A is precise AND accurate

-B is precise, but not accurate

-C is neither accurate nor precise

9- measurement ranges between 2.72 to 2.74 cm

10 -Ans: B

-A has 4 significant digits, because the two zeros count

-B – the “0.0” do not count as two significant digits, therefore 5

significant digits

-C has 2 significant digits, see A for explanation

-D has six significant digits

-*** E is ambiguous: 2 to 5 significant digits because unclear

whether the zeros are significant or placeholders (which means

insignificant)

12 -A: 5

-B: 5

-C 3-5 (for explanation, see slide 10’s E)

-***D is an EXACT QUANTITY therefore significant digits do

not apply

13 - ice is less dense than water therefore it floats on water

14 - Ans: C between the cm³ is able to cancel out

15 -another physical property is smell

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