Cu + O2 --Cu2O a. Write the balanced equation for this reaction.
b. How many grams of Cu are needed to produce 300. grams of Cu2O?
c. How many grams of Cu2O can be produced from 8.0 L of O2 at STP?

a. 4Cu + O₂ → 2Cu₂O

b. 266g Cu

c. 102g Cu₂O

Explanation:

Based on the balanced reaction:

a. 4Cu + O₂ → 2Cu₂O

4 moles of Cu reacts per mole of oxygen to produce 2 moles of Cu₂O.

b. To solve this question we need to find the moles of Cu₂O. With these moles and the balanced reaction we can find the moles of Cu and its mass:

Moles Cu₂O -Molar mass: 143.09g/mol-

300g Cu₂O * (1mol / 143.09g) = 2.097 moles Cu₂O

Moles Cu:

2.097 moles Cu₂O * (4mol Cu / 2mol Cu₂O) 4.193 moles Cu

Mass Cu - Molar mass: 63.546g/mol-

4.193 moles Cu * (63.546g / mol) = 266g Cu

c. In the same way, using PV = nRT we can find the moles of Oxygen. With the moles of oxygen we can find the moles of Cu₂O and its mass:

n = PV / RT

P = 1atm at STP, V = 8.0L, R = 0.082atmL/molK, T = 273.15K at STP:

n = 1atm*8.0L / 0.082atmL/molK*273.15K

n = 0.357 moles O₂

Moles Cu₂O:

0.357 moles O₂ * (2mol Cu₂O / 1mol O₂) = 0.714 moles Cu₂O

Mass Cu₂O -Molar mass: 143.09g/mol-

0.714 moles Cu₂O * (143.09g/mol) =

102g Cu₂O

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most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).