Metric Measurements

Density = grams/cm^3

To What Volume You Dilute A Solution

To what volume should you dilute 20 of a 11.0 solution to obtain a 0.140 solution? 

 

Dilution Equation: M1*V1 = M2*V2

Find out what the final volume,V2, should be as a start.

V2 = M1*V1 / M2

= (11.0M)(20 mL)/(0.140M)

= 1571.42857 mL

 

* 1000 ml = 1 L

1571.42857 mL/1000 = 1.57142857 = 1.6 (rounded to two significant numbers)

Molarity of the Diluted Solution...

If 3.5 of a 5.1 solution is diluted to 40 , what is the molarity of the diluted solution? 

 

Molarity of Diluted Solution = 3.5 X 5.1 = 17.85 / 40 = .44625 = .45 Mor
Molarity of Diluted Solution = 5.1M X (3.5/40)
Molarity of Diluted Solution = .44625 M = .45 M (rounded to two significant numbers)

Mass, Volume, & Molarity of a Solution: Stuff for CHEMISTS

A chemist (ahem, I guarantee any non-chemist will not remember having done this equation during college/etc., even if he or she does it 100 times... and, if they do remember it, maybe they are a genius, but will they ever use it, ponder it, find happiness in life from remembering it...) wants to make 5.0 of a 0.270 solution

 

What mass of (in ) should the chemist use? 

 

Given Volume of the solution , V = 5.0 L

Molarity of the solution , M = 0.270 M

Molar mass of CaCl2: 40.078 + 2(35.453) = 110.984 g /mol

 

Mass of CaCl2 = (V) x (Molarity) x (Molar Mass of CaCl2)

 

5.0 X .270 X 110.984 = 149.8284 = 150 (rounded to two significant numbers)

How Many Moles In A Solution... (Shout out to God for making this simple)

Tidbits you can't simply live life without... . . . . . . . 

• The concentration of a solution is usually given in moles per litre (mol L-1 OR mol/L). This is also known as molarity. 
• Concentration in mol/L or mol L^-1, or Molarity, is given the symbol c (sometimes M).
    Examples:
          [HCl] = 0.01 mol L^-1 (concentration implied by square brackets around formula)
  or
          c(HCl) = 0.01 mol L^-1 (c stands for concentration, formula given in brackets) 

c = n ÷ V

      c = concentration of solution in mol L^-1 (mol/L or M),
      n = moles of substance being dissolved (moles of solute),
      V = volume of solution in litres (L)

moles of solute given molarity and volume of solution: n = c x V 
volume of solution given moles of solute and molarity: V = n ÷ c 

Example/s:

How many moles of are contained in each of the following?

1.6 of a 0.92 solution 
 
.92M =  n / 1.6L
or
n = .92M X 1.6L

n = 1.472 = 1.5 mol (rounded to two significant numbers)


126 of a 1.73 solution 

* 1 Liter = 1000 Milliliters
* 1 Milliliter = 0.001 Liter

126mL =  0.126 liters

n = 1.73 X .126L

n = .21798 =  .218 mol (rounded to three significant numbers)


0.602 of a 2.0 solution  

n = 2.0 X .602L

n = 1.204 = 1.2 mol  (rounded to two significant numbers) 

The "Mole" Explained: Yay