Dimensional analysis

Question 1

When doing cubic relationship qs

Answer 1

1. You know that 1 (cm) = 5.32 n for example
2. c(cm³) means volume so a cubic centimeter is 3D space, so you need to think in three directions (length, width, height).
3. cube the conversion factor
4. e.g 5.32×5.32×5.32=150.56
5. you just multiply your given volume (6.42 cm³) by 150.72 to convert it to cubic nogs.

Question 2

when trying to find mass of metal in a compound i do…

Ca makes up 20.1% of the mass of the calcium-containing compound calcium bromide, CaBr2. If there are 38.3 g of calcium present in a sample of calcium bromide, what is the total mass of the sample?

Answer 2

1. Ca makes up 20.1% of the total mass of (CaBr₂).
   - means that for every 100 g of CaBr = 20.1 g of it is calcium.
   - If calcium is 20.1% of the total mass, and you know the amount of calcium (38.3 grams)
   - 0.201×X=38.3
   - 3.83/0.201
   - x =190.45

Question 3

Determine the value of a:

log a = 3.253

Answer 3

• a is the number whose logarithm (base 10) = 3.253.
• To find a, we need to reverse the logarithm
• ## a=10 ^ 3.253

Question 4

Simplify: 𝑎^5/𝑎^−2

Answer 4

1. we subtract the exponents:
2. Subtracting a negative is the same as adding:
3. 5−(−2)=5+2=a^7.
   4.

Question 5

how to solve If 42% of a number is 18, what is the number?

Answer 5

1. We know that 42% of x is 18.
2. To find x, divide both sides of the equation by 0.42
3. 18/0.42
4. x=42.86

Question 6

calculating pH based on hydronium ion concentration and vice versa

Answer 6

• pH=−log[H30+]
• f you’re given a logarithmic equation and you want to solve for what’s inside the logarithm [H30+], you have to “undo” the log.
• log [H30+] = −5.53 means H30+ —> 10 ^−5.53
  .

Question 7

unit of measurment

Answer 7

Length: meter (m)
Mass: kilogram (kg)
Time: second (s)
Volume: liter (L)

Question 8

sig fig rules

Answer 8

• Non-zero digits are always significant.
• Zeros between non-zero digits are significant.
• Leading zeros (before non-zero digits) are NOT significant.
• Trailing zeros after a decimal point are significant.

Question 9

examples of sig figs

Answer 9

0.00560 → 3 significant figures (5, 6, 0).
1200 → 2 significant figures (1, 2).

Question 10

Solve these
**Addition: **
12.34+0.006+1.2 (Round to the correct number of significant figures.)
**Subtraction: **
100.00−0.567 (Round appropriately.)
**Division: **
125.0÷2.5

Answer 10

• 13.5 BECAUSE round to 2 dp (least precise term is 1.2 with 1 decimal place)
• 99.433 BECAUSE round to 3 dp (least precise term is 0.567)
• 50 BECAUSE round to 3 significant figures (least precise input, 2.5, has 2 sig figs