Anonymous

# chem hw help please? thank you :)?

assume that 5.6 L H2 at STP reacts with CuO according to the following equation-

CuO(s) + H2(g) -------> Cu(s) + H2O(g)

how many moles of H2 react?

how many moles of Cu are produced?

how many grams of Cu are produced?

thanks a lott :)

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at STP, one mole of each gas will be 22.4L according to Avogadro's principle

so, no of moles of H2=5.6/22.4=0.25

According to your equation, one mole of H2 produce one mole of Cu

So, number of moles of Cu formed is 0.25

atomic weight of Cu is 63.55

Therefore, No of grams of Cu produced=0.25*63.55=15.89 g

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• Anonymous

you would need to know how much CuO you start with, but if you have excess you would do the problem like this

at STP a mole of gas would occupy 22.4 liters of space. u have 5.6 liter so u have to divide 5.6 by 22.4 to find how many moles of hydrogen you have. when you do that u get .25:

5.6 / 22.4 = .25 mol of hydrogen so .25 moles of hydrogen react.

if you look at the equation u see that the coeficents infront of each compound is 1, that means that for every mole of hydrogen that reacts an equal number of moles of Cu is produced, thus if .25 moles of hydrogen reacts .25 moles of Cu is produced.

to find how many grams of Cu is produced you have to multiply the number of moles of Cu, .25, by Coppers molar mass, 63.55 (fwhich can be found on a periodic table). so,

63.55 * .25 = 15.9 grams of copper.

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• 5.6 L of h2 at stp means 2.5 moles as

volume of 1mole of a gas at stp =22.4L

therefore,

2.5moles of h2 reacts with 2.5moles of CuO to give

2.5moles of cu=2.5 x 63.54 grams of Cu is produced

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