Answer to Question #348757 in General Chemistry for blesssings

Question

5.One 55 g 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?

Answer 1

Solution:

270 mg of sodium – 11% of the recommended daily allowance

X mg of sodium – 100% of the recommended daily allowance

Using proportions to find out how many mg of sodium are in the recommended daily allowance:

X mg of sodium = (270 mg × 100%) / (11%) = 2454.545 mg

Therefore, the recommended daily allowance of sodium is 2454.545 mg

Convert mg to g:

(2454.545 mg) × (1 g / 1000 mg) = 2.454545 g = 2.455 g

The molar mass of sodium (Na) is 22.99 g/mol

Therefore,

Moles of Na = (2.455 g Na) × (1 mol Na / 22.99 g Na) = 0.10678 mol Na = 0.107 mol Na

The recommended daily allowance of sodium is 0.107 moles of Na

One mole of any substance contains 6.02×10²³ atoms/molecules

Therefore,

Number of Na atoms = (0.107 mol) × (6.02×10²³ atoms / 1 mol) = 6.44×10²² atoms

The recommended daily allowance of sodium is 6.44×10²² Na atoms

Answer: 0.107 moles and 6.44×10²² atoms of sodium are in the recommended daily allowance