A solution is prepared by mixing 25.0 g H2O and 25.0 g C2H5OH. Determine the mole fractions of each substance.

Mole fraction H₂O → 0.72

Mole fraction C₂H₅OH → 0.28

Explanation:

By the mass of the two elements in the solution, we determine the moles of each:

25 g . 1 mol/ 18g = 1.39 moles of water (solute)

25 g . 1 mol / 46 g = 0.543 moles of ethanol (solvent)

Mole fraction solute = Moles of solute / Total moles

Mole fraction solvent = Moles of solvent / Total moles

Total moles = Moles of solute + Moles of solvent

1.39 moles of solute + 0.543 moles of solvent = 1.933 moles → Total moles

Mole fraction H₂O = 1.39 / 1.933 → 0.72

Mole fraction C₂H₅OH= 0.543 / 1.933 → 0.28

Remember that sum of mole fractions = 1

Mol fraction H2O = 0.72

Mol fraction C2H5OH = 0.28 moles

Explanation:

Step 1: Data given

Mass of H2O = 25.0 grams

Molar mass H2O = 18.02 g/mol

Mass of C2H5OH = 25.0 grams

Molar mass C2H5OH = 46.07 g/mol

Step 2: Calculate moles

Moles = mass / molar mass

Moles H2O = 25.0 grams / 18.02 g/mol

Moles H2O = 1.39 moles

Moles C2H5OH = 25.0 grams / 46.07 g/mol

Moles C2H5OH = 0.54 moles

Step 3: Calculate total moles

Total moles = 1.39 moles + 0.54 moles

Total moles = 1.93 moles

Step 4: Calculate mol fractions

Mol fraction = moles / total moles

Mol fraction H2O = 1.39 moles / 1.93 moles

Mol fraction H2O = 0.72

Mol fraction C2H5OH = 0.54 moles / 1.93 moles

Mol fraction C2H5OH = 0.28 moles

the answer is b. dilution

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.