Week 4 Chemistry And Math Review

Question 1

What is chemistry?

Answer 1

The study of matter and it’s changes

Question 2

What is matter?

Answer 2

Anything that has mass and occupies space

Question 3

What are atoms?

Answer 3

Building blocks of matter. Comprised of protons, neutrons, and electrons

Protons: positive charge
Neutrons: neutral charge
Electrons: negative charge

Question 4

What are the order of operations?

Answer 4

• addition
• subtraction
• multiplication
• division

Combined equations

• multiply and divide FIRST
• THEN add and subtract

If parenthesis or large fraction bars present, these functions are to be performed first

Question 5

What happens when negative numbers are multiplied?

Answer 5

When multiplying 2 negative numbers, the answer is always positive

Question 6

What are inverse operations?

Answer 6

• multiplication/division
• addition/subtraction
• multiplicity identity element = 1
• additive identity element = 0

*when you are trying to isolate a variable use the inverse operations to move things back and forth

Question 7

What are logarithms?

Answer 7

Inverse of a square root

-the log product is the sum of the logs
Log(a x b) = log(a) + log(b)

-the log of a ratio is the difference of the logs
Log(a/b) = log(a) - log (b)

-the log of a power is the exponent in the power times the log of the base power
Log(a to the b power) = b x log(a)

Question 8

What are exponents?

Answer 8

• number of time a quantity are multiplied
• any quantity revised to the zero power = 1
• any quantity to the -1 power equals the reciprocal (except for 0)
• when multiplying, add exponents
• when dividing, subtract exponents

Question 9

What is scientific notation?

Answer 9

• numbers multiplied by a power of 10

- the order of magnitude: how many places to move the decimal place to leave one digit to the left of the decimal point

Question 10

What are significant figures?

Answer 10

• a way to assess reliability
• those number which have physical meaning
• estimate one decimal place beyond the smaller division on the scale.
• non-zero digits are always significant

Question 11

When are zeros significant and not significant?

Answer 11

Significant
– They occur between two significant numbers (ex:308)
– They are to the right of the decimal point and also
to the right of non-zero numbers (ex: 0.30 and 2.0)

Not significant
– A single zero to the left of the decimal point is only a visual reference for the decimal point (ex: 0.15)
– Zeros to the right of a decimal point that proceed a non-zero number (ex: 0.005)
– Zeros to the left of a decimal point following a non-zero number (ex: 40), unless one of these zeros is identified by the recorder as significant by underlining the zero (ex: 40)

Question 12

What is accuracy?

Answer 12

Agreement between experimental date and the “true” value

Question 13

What is precision?

Answer 13

Agreement between replicate measurements

Question 14

What is percent errro?

Answer 14

-calculating the accuracy
-% error = measured value - “true value”. x100%
——————————————-
“True value”

• a greater number of significant figures = greater precision
• precision: quantified by standard deviation

Question 15

What is mean?

Answer 15

Sum of measurements divided by number of measurements

Question 16

What is standard deviation?

Answer 16

Tells you how close you are to the average. Classic bell curve

Question 17

What are the prefixes for the metric system?

Answer 17

• kilo. 1 x 10 to the 3
• deci. 1 x 10 to the -1
• centi. 1 x 10 to the -2
• milli. 1 x 10 to the -3
• micro. 1 x 10 to the -6

Question 18

1 inch equals how many centimeters?

Answer 18

2.54

Question 19

1 kilogram equals how many pounds?

Answer 19

2.2

Question 20

1 mL equals how many cm?

Answer 20

1 cm3

Question 21

What is specific gravity?

Answer 21

• Ratio between an object’s density and the density of water
• doesn’t depend on units
• value >1 is more dense than water, <1 is less dense than water
• specific gravity = density when the units are g/mL