**Determine the molecular weight
of C _{6}H_{12}O_{6}** (glucose).

_{ Element Atomic Weight Number of atoms Weight (g) Carbon 12 6 72 Hydrogen 1 12 12 Oxygen 6 6 96 Molecular weight (sum of the atomic weights) 180 }180 grams of glucose = 1 mole

**How would you prepare 1 liter
of a 1M (molar) solution of glucose
(C _{6}H_{12}O_{6})? a 0.25M
solution?**

- Calculate the number of grams of glucose to give you 1
**mole** - 180 grams of glucose equals 1
**mole**of glucose - 1
**mole**of glucose dissolved in 1 liter of water makes a 1 M (**molar**) solution of glucose - therefore dissolving 180 grams of glucose (= 1 mole of glucose) in 1 liter of water makes a 1M solution.

**what about a 0.25M
solution?**

- First calculate the number of grams of glucose that equals
0.25 moles of glucose:
(180 g) / 1mole = (X g) / 0.25 mole

- cross multiply to give:
(180 g) x 0.25 mole = 1 mole x (X g)

(180 g) x 0.25 mole / 1 mole = X g

X = 45 grams of glucose - dissolving 45 grams of glucose in 1 liter of water will give you a 0.25 M solution.

**How would you prepare 250 ml of
0.3 M solution of NaCl?**

- calculate the number of grams of NaCl to
give you 1 mole
atomic weight of Na = 23 g

atomic weight of Cl = 35.6 g

molecular weight = 58.6 g which equals one mole! - calculate the number of grams of NaCl
that equals 0.3 moles of NaCl
(58.6 g) / 1 mole = (X g) / 0.3 mole

X = 17.6 g

dissolving 17.6 g of NaCl in 1 liter of water would give you a 0.3 M solution of NaCl. - We only want 250 ml of a 0.3 M solution
of NaCl
(17.6 g / 1 liter) x (1 liter / 1000 ml) = X g / 250 ml

17.6 g / 1000 ml = X g / 250 ml

17.6 g x 250 ml / 1000 ml = X g

X = 4.4 g