Question

A sample of gold (Au) has a mass of 72.04 g.

A) Calculate the number of moles of gold (Au) in the sample. Show your work and highlight your final answer.

Calculation:

B) A sample of gold (Au) has a mass of 72.04g. Calculate the number of atoms of gold (Au) in the sample. (Use your answer from Part A.) Show your work and highlight your final answer.

Calculation:






Question 2 A sample of sodium chloride (NaCl) has a mass of 16.55 g.
A) Calculate the number of moles of NaCl in the sample. Show your work and highlight your final answer.

Calculation

B) A sample of NaCl (sodium chloride) has a mass of 16.55g. Calculate the number of moles of Na (sodium). Calculate the number of moles of Cl (chlorine). (Hint; you can use your answer from Part A as your starting point.) Show your work and highlight your final answer.

Calculation

C) A sample of NaCl (sodium chloride) has a mass of 16.55g. Calculate the number of atoms of Na (sodium). Calculate the number of atoms of Cl (chlorine). (Hint; you can use your answer from Part B as your starting point.) Show your work and highlight your final answer.
Calculation:





Question 3 A sample of table sugar (sucrose, C12H22O11) has a mass of 5.432 g.


A) Calculate the number of moles of C12H22O11 in the sample. Show your work and highlight your final answer.

Calculation

B) A sample of table sugar (sucrose, C12H22O11) has a mass of 5.432 g. Calculate the number of moles Carbon. Calculate the number of moles Hydrogen. Calculate the number of moles Oxygen. (Hint: You can use your answer from Part A as your starting point.) Show your work and highlight your final answer.

Calculation

C) A sample of table sugar (sucrose, C12H22O11) has a mass of 5.432 g. Calculate the number of atoms Carbon. Calculate the number of atoms Hydrogen. Calculate the number of atoms Oxygen. (Hint: You can use your answer from Part B as your starting point.) Show your work and highlight your final answer.

Calculation

Answer 1

A) 0.365 mole

B)2.198 x 10^23 atoms

For 2A

A) 0.2831 mole

Step-by-step explanation:

number of moles (n)= Mass / Molecular weight

Number of atoms (N) = moles x Avogadro number

A) n = 72.04 / 196.97 = 0.365 moles

b) N= 0.365 x 6.023 x 10^23 = 2.198 x 10^23 atoms

for 2A

Molecular weight for NaCl

Na = 22.99 , Cl = 35.45

so Mw = 22.99 + 35.45 = 58.44

A) n = 16.55 / 58.44 = 0.2831 mole

Answer 2

Question 1 : A) 0.365 mole , B) 2.2 * 10^23 atoms

Question 2: A) 0.283 mole , B) 0.283 mole , C) 1.7 * 10^23 atoms

Question 3: A) 0.016 mole ; B) C: 0.192 mole, H: 0.352 mole, O: 0.176 mole; C) C: 1.16 * 10^23 atoms, H: 2.12 * 10^23 atoms, O: 1.06 * 10^23 atoms

Step-by-step explanation:

Question 1

A) Number of moles are calculated with the following formula:

number of moles = Mass / Molecular weight

mass of gold = 72.04 g

Molecular weight of gold = 197 g/mole

number of moles of gold = 72.04 / 197 = 0.365 mole

B) To calculate the number of atoms, the Avogadro number is needed, as follows :

Number of atoms = moles * Avogadro number

Avogadro number = 6.023 * 10^23 atoms/mole

Number of atoms of gold = 0.365 * 6.023 * 10^23 = 2.2 * 10^23 atoms

Question 2

A) Following the same procedure as before

mass of NaCl = 16.55 g

Molecular weight of NaCl = 35.5 + 23 = 58.5 g/mole

number of moles of NaCl = 16.55 / 58.5 = 0.283 mole

B) Each molecule of NaCl has 1 atom of Na and 1 atom of Cl, that means each mole of NaCl has 1 mole of Na and 1 mole of Cl, so:

number of moles of Na = 0.283 mole

number of moles of Cl = 0.283 mole

C) Following the same procedure as before

Number of atoms of sodium = Number of atoms of chlorine = 0.283 * 6.023 * 10^23 = 1.7 * 10^23 atoms

Question 3

A) Following the same procedure as before

mass of sucrose = 5.432 g

Molecular weight of sucrose = 342.3 g/mole

number of moles of sucrose = 5.432 / 342.3 = 0.016 mole

B) Each molecule of C12H22O11 has 12 atoms of C, 22 atoms of H and 11 atoms of O, that means each mole of C12H22O11 has 12 moles of C, 22 moles of H and 11 moles of O, so:

moles of C = 12*0.016 = 0.192 mole

moles of H = 22*0.016 = 0.352 mole

moles of O = 11*0.016 = 0.176 mole

C) Following the same procedure as before

Number of atoms of C = 0.192 * 6.023 * 10^23 = 1.16 * 10^23 atoms

Number of atoms of H = 0.352 * 6.023 * 10^23 = 2.12 * 10^23 atoms

Number of atoms of O = 0.176 * 6.023 * 10^23 = 1.06 * 10^23 atoms