Unit 1: fundamentals

Question 1

What are the 7 fundamental units?

Answer 1

• Kilogram (kg)
• Length (m)
• Second (s)
• Kelvin (k)
• Ampere (A)
• Mole (mol)
• Candela (cd)

Question 2

What’s mass?

Answer 2

Amount of matter (anything physical) in a object
- kilogram (kg)

Question 3

What’s length?

Answer 3

Distance light travels in a vacuum in/1299 792 458 of a secon
- meter (m)

Question 4

What’s temperature?

Answer 4

Measure of the kinetic energy of molecular movement
- Kelvin (K)
- K = C + 273.15

Question 5

What’s weight?

Answer 5

Measure of gravitational force on an object.
- kg (m/s2) or newton, N

Question 6

What’s volume?

Answer 6

Amount of space occupied by an object.
- m3 or L, mL… (1 cm3 = 1mL)

Question 7

What’s density ?

Answer 7

Relates the mass of an object to it’s volume.
- SI unit = g/cm3 or g/mL
- Temperature dependent, but independent of sample size

Question 8

Accuracy?

Answer 8

How close a particular measurement is to the true value?

Question 9

Precision?

Answer 9

How well different measurements agree with each other

Question 10

Uncertainty of analog devices?

Answer 10

• Uses continuous scale, so uncertainty is +/- the half the smallest increment
• Ex: ruler

Question 11

Uncertainty of digital devices?

Answer 11

• Uses digital scale
• Uncertainty = +/- least significant digit

Question 12

What’s a significant figure?

Answer 12

Defined as the number of digits in a given value, or measurement, that reflects the accuracy and precision of measurement.

Question 13

Rules of significant figures?

Answer 13

1. Non zero integers are always significant (ex: 3)
2. Zeros in the middle of a number are always significant (ex: 4803)
3. Zeros at the beginning are not significant (ex: 0.00661)
4. Zeros at the end are significant if after decimal (ex: 66.110)
5. Zeros at the end of number and before the decimal may or may not be significant (ex: 66110)
6. Exact numbers are known with certainty, so not considered in calculations (ex: 3 mol)

Question 14

Rounding rules?

Answer 14

• Drop non-significant digits and adjust the last digit in the FINAL RESULT of a calculation.
• If 5 or greater, round up and drop all digits farther to the right
• If less than 5, round to SF and drop all digits to the right.

Question 15

Significant figures in calculations?

Answer 15

1. Multiplication/division
   - Answer needs to have same significant figures as the measurement with smallest number of significant figures
2. Addition or substraction
   - Answer as same number of decimal places as the smallest number

*If there is a exact number, don’t consider in calculations

Question 16

Prefixes?

Answer 16

• Tera = T = 10*12
• Giga = G = 10*9
• Mega = M = 10*6
• Kilo = k = 10*3
• Hecto = h = 10*2
• Deka = da = 10*1
• Deci = d = 10*-1
• Centi = d = 10*-2
• Milli = m = 10*-3
• Micro = u = 10*-6
• Nano = n = 10*-9
• Pico = p = 10*-12
• Fento = f = 10*-15

Question 17

Scientific notations?

Answer 17

• Expresses very large or very small numbers
• Expressed as product of a number between 1-10 that is multiplied by a power of 10

Question 18

Dimensional analysis?

Answer 18

• Used to facilitate long calculations to write them in one line
• Uses conversion factors
• Only multiplication/division no addition or substraction