Answer:
3 grams C₅H₁₀O₅
Step-by-step explanation:
To find the mass of ribose needed to prepare the sample, you need to
(1) convert the volume from mL to L (1,000 mL = 1 L)
(2) calculate the number of moles (M = moles / L)
(3) convert moles to grams (using the molar mass of ribose)
The molecular formula of ribose is C₅H₁₀O₅. It is important to arrange all of the ratios/conversions in a way that allows for the cancellation of units.
(Step 1)
200 mL C₅H₁₀O₅ 1 L
---------------------------- x ---------------------- = 0.2 L C₅H₁₀O₅
1,000 mL
(Step 2)
Molarity (M) = moles / volume (L) <----- Molarity ratio
0.1 M = moles / 0.2 L <----- Insert values
0.02 = moles <----- Multiply both sides by 0.2 L
(Step 3)
Atomic Mass (C): 12.011 g/mol
Atomic Mass (H): 1.008 g/mol
Atomic Mass (O): 15.999 g/mol
Molar Mass (C₅H₁₀O₅): 5(12.011 g/mol) + 10(1.008 g/mol) + 5(15.999 g/mol) = 150.13 g/mol
0.02 moles C₅H₁₀O₅ 150.13 g
---------------------------------- x ------------------- = 3 grams C₅H₁₀O₅
1 mole