EMPIRICAL FORMULA OF COPPER OXIDE: Late Nite Labs

One of the copper oxides has the formula Cu2O. What is the oxidation state of the copper in this compound? a. 2- b. 2+ c. 1+ d. 0 e. None of the above

c. 1+

The total mass of product after heating and cooling it was 12.518 g. Assuming none of the original copper was lost, what number is subtracted from this number to get the mass of oxygen in the product? a. 10.0 grams b. 2.518 g c. 3.203 g d. 8.00 g e. None of the above

a. 10.0 grams

In Experiment One 10 grams of copper is reacted with oxygen in the air. How many moles of copper is this? a. 6.355 mol Cu b. 0.1574 mol Cu c. 0.3448 mol Cu d. 0.0157 mol Cu e. None of the above

b. 0.1574 mol Cu

What is the mass of the copper oxide after heating? Choose the closest answer. A. 12.518 g B. 100.518 g C. 9.225 g D. 3.447 g

A. 12.518 g

What was the mass of the crucible after the addition of copper? A. 98.000 g B. 95.000 g C. 88.000 g D. 100.518 g

A. 98.000 g

How many moles of copper (II) sulfate pentahydrate were used in the reaction? The molar mass of copper (II) sulfate pentahydrate is 249.68 g/mol. For best accuracy use the mass measured with the balance during the experiment. Choose the closest answer. A. 0.3605 moles B. 0.02002 moles C. 0.3404 moles D. 0.04005 moles

B. 0.02002

What happened when NaOH was added to the copper (II) sulfate pentahydrate solution? A. Nothing happened B. A blue precipitate formed C. an orange precipitate formed D. a green precipitate formed

B. A blue precipitate formed

What was the identity of the precipitate that formed in experiment 2 upon the addition of NaOH? A. copper metal B. copper hydroxide C. copper sulfate D. copper oxide

B. Copper Hydroxide

Lithium is the only metal that reacts with nitrogen gas at room temperature to form lithium nitride. To avoid oxide formation, the reaction is performed under pure nitrogen gas. Given the experimental data in the table below, what is the empirical formula of lithium nitride? The molar mass of lithium is 6.94 g/mol and of nitrogen is 14.01 g/mol. A. Li N2 B. Li3N C. LiN D. LiN3

B. Li3N

What is the empirical formula of copper oxide based on your results in experiment 1? A. Cu203 B.CuO C. Cu2O D. CuO2

B.CuO

The copper changed to copper oxide upon heating. How many grams of oxygen were used in the reaction? Choose the closest answer. A. 7.992 g B. 1.042 g C. 2.518 g D. 3.664 g

C. 2.518 g

How many grams of copper (II) sulfate pentahydrate were added to the beaker? A. 1.000 g B. 2.000 g C. 5.000 g D. 10.000 g

C. 5.000 g

What was the color of the copper before heating? A. black B. blue-black C. red-orange D. white

C. Red-orange

What was the color of the copper oxide after heating? A. green B. orange C. black D. blue

C. black

In Experiment 2, what color was the copper (II) sulfate pentahydrate before heating? A. white B. yellow C. blue D. black

C. blue

Suppose you were to heat the copper in argon gas instead of atmospheric gasses. Given that argon is relatively inert, which of the following would you expect if you were to heat pure copper in the presence of argon gas?

Copper oxide would not form and the mass would not change

The molar mass of copper is 63.55 g/mol. How many moles of copper were reacted? A. 0.6724 mol B. 0.8822 mol C. 1.5421 mol D. 0.1574 mol

D. 0.1574

The molar mass of oxygen is 16.00 g/mol. How many moles of oxygen are in copper oxide? A. 0.7824 mol B. 6.2824 mol C. 0.4785 mol D. 0.1574 mol

D. 0.1574

What is the molar ratio of copper to oxygen in the copper oxide formed in experiment 1? A. 2:1 B. 1:2 C. 3:2 D. 1:1

D. 1:1

In Experiment 1, what was the mass of the empty crucible? A. 90.000 g B. 98.000 g C. 95.000 g D. 88.000 g

D. 88.000 g

Both experiments gave rise to the same formula for copper oxide. What is it? a. CuO4 b. CuO2 c. Cu2O d. CuO e. None of the above

d. CuO

A student decides to reverse the process and turn copper oxide into pure copper. How much pure copper can she get from 106 g CuO? The balanced equation is 2CuO → 2Cu + O2 a. 79.9 % of 106 g b. 169.4 g c. 84.7 g d. 63.6 % of 106 g e. Both (a) and (c) are correct.

e. Both (a) and (c) are correct.

In Experiment Two the blue solid from the beaker was transferred to a test tube and heated. What happened during this step of the process? a. The sulfate turned into sulfur dioxide vapor. b. Copper hydroxide was converted to copper oxide. c. Copper was melted into a black solid. d. Water vapor was driven out of the test tube by the heat. e. Both (b) and (d) are correct.

e. Both (b) and (d) are correct.