Prequiz: Chem121
Name:_____________________________
1. Fill in the blanks for the following element:
119
Sn
Number of protons__50___
Mass Number__119__
Number of electrons__50___
Atomic Number_50___
Number of neutrons__69__
Name of element___Tin_____________
2. What subatomic particle(s) are found in the nucleus of the atom?___protons and
neutrons__
3. How many total atoms (or moles) are contained in the molecule ammonium nitride:
(NH4)3N 16
3. Calculate the Molar Mass for the molecule calcium hydroxide: Ca(OH)2
74.10 g/mole
4. How many grams of potassium, chemical symbol, K are contained in 2.65 moles of
potassium?
2.65 mole K
39.10 g K
1 mole K
= 104 g K
5. How many atoms of chlorine, chemical symbol Cl, are in 17.40 grams of chlorine?
17.40g Cl
1 mole Cl
6.022 x 10^23 atoms Cl
35.45 g Cl
1 mole Cl
= 2.956 x 10^23 atoms Cl
6. Bicarbonate of soda (sodium hydrogen carbonate) is used baking. Its formula is NaHCO3.
Calculate the Mass Percent Composition (mass %) of Na (sodium) in sodium hydrogen
carbonate.
Assume 1 mole of NaHCO3 Molar Mass = 84.01 g/mole
Then, Molar Mass of Na as part of NaHCO3 = 22.99 g/mole
Percent Mass of Na = 22.99/84.01 x 100 = 27.37%