1. Using the method described in the lab, you wanted to determine the formula of
ID: 561312 • Letter: 1
Question
1. Using the method described in the lab, you wanted to determine the formula of the transition metal oxide, zinc oxide. Starting with 3.145 g of zinc you formed 3.915 g of oxide. Determine the mass of oxygen in this compound. Express your answer in grams as three significant digits. 2. Is this compound (circle one): a. covalent b. elemental c. ionic d. undeterminable 3. Calculate the empirical formula and molecular formula of the compound. Calculate the percentage by mass of the elements in the compound. Express your answers as three significant digits. 4.Explanation / Answer
Q1.
mass of oxygen = (Mass of oxide ) - (Metal) = 3.915-3.145 = 0.770 g
Q2
the compound (oxide) must be ionic, since Zn+2 and O-2 are charged
Q3
empirical formula
mol of Zn = mass/MW = 3.145/65.39 = 0.048
mol of O = mass/MW = 0.77/16 = 0.048125
raito 0.048125 /0.048 = 1
Zn:O
ZnO
Q4.
% by mass of Zn = mass of Zn /Y Total mass * 100 = 3.145/3.915*100 = 80.33%
% mass of O = 100-80.33 = 19.67% for O
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