1. How many atoms of gold are there in a 1 cubic inch of gold? The density of go

Question

1. How many atoms of gold are there in a 1 cubic inch of gold? The density of gold is 19.32 g/cm3 and 1 cubic inch = 16.39 cm3.

2. How many molecules of aspirin are there in a 200mg tablet? The chemical formula of aspirin is C9H8O4.

3. In the following reaction, aluminum sulfate Al2(SO4)3 and calcium hydroxide Ca(OH)2 react to produce calcium sulfate CaSO4 , and aluminum hydroxide Al(OH)3. Answer the questions in parts a, b, c, d, and e.

a) In the reaction above ______ moles of Ca(OH)2 are needed to produce _______ moles of Al(OH)3 . (fill in the blanks)

b) How many moles of calcium hydroxide that is required to produce 60 moles of aluminum hydroxide.

c) What is the molar mass of Ca(OH)2 ?

d) What is the molar mass of Al(OH)3 ?

e) What mass of calcium hydroxide Ca(OH)2 is required to produce 78.0 g of aluminum hydroxide Al(OH)3?

Hi all, I need help getting the responses to these questions please. Please help me see the solution process. Thanks in advance for your help.

Explanation / Answer

1.

Solve for the mass of gold from the density:

1 cubic inch x 16.39 cm^3 / 1 cubic inch x 19.32 g / cm^3 = 327.09 g

Solve for the moles of gold from its molar mass:

327.09 g x 1 mol / 196.97 g = 1.66 moles

Solve for the number of gold atoms from Avogadro's constant:

1.66 moles of gold x (6.022 x 10^23 gold atoms) / 1 mole of gold = 9.99 x 10^23 gold atoms

2.

Solve for the moles of aspirin from its molar mass:

200 mg x 1 g/1,000 mg x 1 mol/180.16 g = 0.00111 moles

Solve for the number of aspirin molecules from Avogadro's constant:

0.00111 moles of aspirin x (6.022 x 10^23 aspirin molecules) / 1 mole of aspirin

= 6.68 x 10^20 aspirin molecules

a)

3 moles of Ca(OH)2, 2 moles of Al(OH)3

c)

40.08 + (2 x 16.00) + (2 x 1.01) = 74.09 g/mol

d)

26.98 + (3 16.00) + (3 x 1.01) = 78.00 g/mol

e)

First, solve for the moles of Al(OH)3:

78.0 g x 1 mol/78.00 g = 1 mole

Now, solve for the moles of Ca(OH)2 using the balanced chemical equation:

1 mole of Al(OH)3 x 3 moles of Ca(OH)2 / 2 moles of Al(OH)3 = 1.5 moles

Now, solve for the mass of Ca(OH)2 from its molar mass:

1.5 moles x 74.09 g / mol = 111.14 g

Hope this helps! :)

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