Chemistry 11
Mass, Molar Mass and Avogadro’s Number
This lab consists of 7 vials, each containing a different compound. Before beginning obtain one of the empty vials
and record its mass to the nearest 0.01 g. For each part (1 - 7): mass the vial then subtract the mass of the
empty vial, this is the mass of the compound in the vial. Complete the calculations indicated in each part. Submit
your group’s data to me.
Samples
1. Mossy tin is formed by dropping hot liquid tin particles into cold water, the resulting little droplets are pure Sn(s).
a. what is the mass of tin present in the vial?
b. how many moles of tin are in the vial?
c. how many atoms of tin are in the vial?
2. The yellow powder in the vial is elemental sulfur, S8(s).
a. what is the mass of sulfur in the vial?
b. how many moles of sulfur are present?
c. how many sulfur atoms are present? (before your answer have a look at the above formula for sulfur)
3. Pencil “lead” is not actually lead, it is essentially graphite, an allotrope of carbon written as C (graphite). We, the
Chemistry teachers, spent an afternoon in the chemistry lab meticulously counting carbon atoms but then lost
their count. Please help us.
a. what is the mass of carbon in the vial?
b. how many atoms of carbon are present?
4. Calcium carbonate can be found as an ingredient in chalk or in a metamorphic rock form as marble.
a. what is the mass of calcium carbonate in the vial?
b. how many moles does this represent?
c. how many OXYGEN atoms are present in the sample?
5. Sucrose is what we commonly refer to as table sugar. Its formula is C12H22O11.
a. what is the mass of the sucrose in the vial?
b. how many molecules of sucrose are present?
c. how many hydrogen atoms are present in the sample?
6. Lauric acid or docecanoic acid is a common ingredient in soaps. Its formula is C12H24O2.
a. what is the mass of the sample?
b. what is the mass of all of ONLY the hydrogen in the sample?
c. how many atoms make up the entire sample?
7. Methanol, CH3OH, has a density of 0.79 g/mL (think conversions we’ve looked at, example: seconds to years).
Mr Hubley and myself think we poured 35.60 mL of methanol into the vial. Determine if we are correct.
a.
b.
c.
d.
what is the mass of the methanol in the vial?
what would the volume of the methanol you massed in part a?
are Mr. Hubley and myself correct?
how many molecules of methanol are present in the vial?