180k views
5 votes
One 55-gram serving of a particular cereal supplies 270 mg of sodium, 11% of the recommended daily allowance. How many moles and atoms of sodium are in the recommended daily allowance?

a) Moles: 3.6×10−3, Atoms: 2.17×1021
b) Moles: 5.4×10−3, Atoms: 3.26×1021
c) Moles: 4.8×10−3, Atoms: 2.89×1021
d) Moles: 2.2×10−3, Atoms: 1.32×1021

1 Answer

3 votes

Final answer:

To calculate the moles and atoms of sodium in the RDA for sodium, we first determine the total amount of sodium recommended which is 2454.545 mg.

Step-by-step explanation:

To determine how many moles and atoms of sodium are in the recommended daily allowance (RDA) based on the information provided, we'll need to work through a couple of calculations. The 55-gram serving of the cereal supplies 270 mg of sodium, which is 11% of the RDA. To find the total amount of sodium in the RDA, we calculate:

RDA for sodium = (270 mg) / (11%)
= (270 mg) / (0.11)
= 2454.545 mg

This is the total amount of sodium recommended daily. Now to find the number of moles, we use the molar mass of sodium (Na), which is approximately 22.99 g/mol. However, we should convert the mass of sodium from milligrams to grams first:

RDA for sodium in grams = 2454.545 mg × (1 g / 1000 mg)
= 2.454545 g

Now, we calculate the moles of sodium:

Moles of sodium = (mass of sodium) / (molar mass of sodium)
= (2.454545 g) / (22.99 g/mol)
= 0.106788 mol ≈ 1.07 × 10^(-1) mol

To find the number of atoms, we use Avogadro's number, which is approximately 6.022 × 10^(23) atoms/mol. We multiply the moles of sodium by Avogadro's number:

Atoms of sodium = (moles of sodium) × (Avogadro's number)
= (1.07 × 10^(-1) mol) × (6.022 × 10^(23) atoms/mol)
= 6.45 × 10^(22) atoms

Therefore, none of the provided answer options (a through d) correctly states the moles and atoms of sodium in the recommended daily allowance.

User John Polling
by
7.1k points

Related questions