Math & Unit Conversions
How many significant figures are in the number 0.00204790?
6
What is the name of the compound NO?
Nitrogen monoxide
Phosphorous-33 contains...
a. 33 protons
b. 18 neutrons
c. 33 neutrons
d. 18 protons
b. 18 neutrons
Consider the ratio of the mass of oxygen in carbon monoxide vs. carbon dioxide. What law is the difference an example of?
Law of multiple proportions
A sample of bronze has a volume of 0.225 L. The density of bronze is 7.8 g/mL. What is the mass of the sample?
1.8x103 g
What is the name of HCH3COO?
Acetic acid
How many molecules of oxygen gas are in a pure 200. g sample?
3.76 x 1024
What is the percent composition of chromium in K2Cr2O7?
35.4%
The density of a certain substance is 6.3 g/cm3. Aliens have landed on your planet and demand that properties be expressed in their units of density, glorps/eeks3. 1 glorp = 0.324 g, and 1 cm = 2.7 eeks. What is the density in alien units?
0.988 glorps/eeks3
Write the chemical formula for Cobalt(II) chlorate dihydrate.
Co(ClO3)2 2H2O
Calculate the atomic mass of Zinc assuming the three following isotopes and abundances. 64Zn: 63.929 amu, 51.3%, 66Zn: 65.926 amu, 29.8%, 68Zn: 67.925 amu, 18.9%
65.279 amu
What is the molecular formula of a compound that has a mass of 32.06 g/mol and an empirical formula of NH2?
N2H4
The recommended infant dose of acetaminophen is 12.5 mg/kg of body mass every four hours. If acetaminophen is available in liquid form with a concentration of 160 mg/5.0 mL, how many mL should be administered to an infant weighing 8.9 lbs? 1kg = 2.2 lbs
1.58 mL
Solid iron reacts with aqueous acetic acid to form aqueous iron(III) acetate and hydrogen gas. Write the correct balanced chemical equation for this reaction.
2Fe(s) + 6HC2H3O2(aq) --> 2Fe(C2H3O2)3(aq) + 3H2(g)
Gallium has 2 isotopes and the average mass of 69.72 amu. Find the abundance of these isotopes: 69Ga = 68.93 amu, 71Ga = 70.92 amu
69Ga: 60.3% 71Ga: 39.7%
An oxide of lead contains 90.67% Pb, by mass. What is the empirical formula?
Pb3O4