Question

How many moles are in 10.23 g of PO4-3? How many moles are 8.25 x 10^28 molecules of Na2CO3? What is the mass of 6 moles of CH2O? How many formula units are in 6.34 g of NaCl? How many ions are in 0.25 moles of Cu+2? How many grams are in 3.4 x 10^24 molecules of CH4? How many moles are in 10 mL of water (density of water = 1 g/mL)? (sorry for so many questions in one)

Answer 1

1) 0.1077 moles

2) 137043.2 moles

3) 180.186 grams

4) 6.53×10²² molecules or formula units

5) 1.505×10²³ ions

6) 90.626 grams

7) 0.555 moles

Step-by-step explanation:

1) The number of moles, n = Mass of the substance/(Molar mass of the substance)

The molar weight of PO₄⁻³ is 94.971 g/mol

The number of moles in 10.23 g of PO₄⁻³ is n =10.23/94.971 = 0.1077 moles

The number of moles in 10.23 g of PO₄⁻³ = 0.1077 moles

2) The number of molecules of Na₂CO₃ in one mole of Na₂CO₃ is given by the Avogadro's number,
`N_A` = 6.02 × 10²³ molecules

Therefore, the number of moles in 8.25 × 10²⁸ molecules of Na₂CO₃ is found by determining how many Avogadro's number of molecules are in 8.25 × 10²⁸ molecules of Na₂CO₃ as follows;

The number of moles in 8.25 × 10²⁸ molecules of Na₂CO₃ = (8.25 × 10²⁸)/(6.02 × 10²³) = 137043.2 moles

The number of moles in 8.25 × 10²⁸ molecules of Na₂CO₃ = 137043.2 moles

3) The molar mass of CH₂O = 30.031 g/mol

Therefore, the mass of 6 of CH₂O = 6 moles × 30.031 g/mol = 180.186 grams

The mass of 6 of CH₂O = 180.186 grams

4) The molar mass of NaCl = 58.44 g/mol

The number of moles of NaCl in 6.34 g of NaCl 6.34/58.44 = 0.1085 moles

1 formula unit of NaCl = 1 molecule of NaCl

The number of molecules in one mole of a substance =
`N_A` = 6.02 × 10²³

Therefore, the number of molecules in 0.1085 moles of NaCl = 6.02 × 10^(23) × 0.1085 = 6.53×10²² molecules or formula units

5) The number of ions per mole of any substance is give by Avogadro's number,
`N_A` = 6.02 × 10²³ ions,

The number of ions in 0.25 moles of Cu⁺² = 0.25×6.02 × 10²³ ions = 1.505×10²³ ions

The number of ions in 0.25 moles of Cu⁺² = 1.505×10²³ ions

6) The molar mass of CH₄ = 16.04 g/mol

The number of moles, n, in 3.4×10²⁴ = 3.4×10^(24)/(6.02×10^(23)) = 5.65 moles 5.65*16.04

The mass of 5.65 moles of CH₄ = 5.65 moles × 16.04 g/mol = 90.626 grams

The mass of 3.4×10²⁴ molecules of CH₄ = 90.626 grams

7) The density of water = 1 g/mL

The volume of the water 10 mL

The mass of the water = Volume × Density = 10 mL × 1 g/mL= 10 grams

The molar mass of water = 18.015 g/mol

The number of moles of water in 10 g of water = mass/(Molar mass) = 10/18.015 = 0.555 moles.