Antifreeze Ethylene glycol is the common name for the liquid...

Antifreeze Ethylene glycol is the common name for the liquid used to keep the coolant in automobile cooling systems from freezing. It is $38.7 \%$ carbon, $9.7 \%$ hydrogen, and $51.6 \%$ oxygen by mass. Its molar mass is $62.07 \mathrm{g} / \mathrm{mol}$ and its density is $1.106 \mathrm{g} / \mathrm{mL}$ at $20^{\circ} \mathrm{C}$ a. What is the empirical formula of ethylene glycol? b. What is the molecular formula of ethylene glycol? c. In a solution prepared by mixing equal volumes of water and ethylene glycol, which ingredient is the solute and which is the solvent?

Antifreeze Ethylene glycol is the common name for the liquid used to keep the coolant in automobile cooling systems from freezing. It is $38.7 \%$ carbon, $9.7 \%$ hydrogen, and $51.6 \%$ oxygen by mass. Its molar mass is $62.07 \mathrm{g} / \mathrm{mol}$ and its density is $1.106 \mathrm{g} / \mathrm{mL}$ at $20^{\circ} \mathrm{C}$
a. What is the empirical formula of ethylene glycol?
b. What is the molecular formula of ethylene glycol?
c. In a solution prepared by mixing equal volumes of water and ethylene glycol, which ingredient is the solute and which is the solvent?

Key Concepts

Empirical Formula Determination

This concept involves using the percentage composition by mass of each element in a compound to determine the simplest whole-number ratio of atoms present. By converting mass percentages to moles and then normalizing by the smallest amount in the set, one obtains the empirical formula, which represents the basic proportional makeup of the molecule.

Molecular Formula Determination

After establishing the empirical formula, the molecular formula is obtained by comparing the empirical formula’s mass to the known molar mass of the compound. The molecular formula shows the actual number of atoms of each element in a single molecule, which is found by multiplying the empirical formula by an appropriate whole-number factor.

Solute and Solvent in Solutions

This concept distinguishes between the two primary components of a solution. The solvent is the component present in the greater amount and is typically responsible for dissolving the solute, which is present in a smaller amount. In mixed solutions, determining which substance acts as the solvent is generally based on its relative quantity and its role in forming the homogeneous mixture.

Transcript

00:01 Here in this problem given anti -freeze ethylene glycol is the common name for the liquid used to keep the coolant in automobile cooling system from freezing.

00:10 It is 38 .7 percent carbon, 9 .7 percent hydrogen and 51 .6 percent oxygen biomass.

00:17 Molar mass given here and density given here.

00:21 We have to find out the empirical formula of ethylene glycol, then molecular formula of ethylene glycol, then we have to determine in a solution prepared by mixing equal volumes of water and ethylene glycol which ingredient is the solute and which is the solvent.

00:39 First if we have 100 grams of a sample then we have 38 .7 grams of carbon, 9 .7 grams of hydrogen and 51 .6 grams of oxygen.

00:58 Now we will find out moles of carbon and moles of hydrogen and moles of oxygen.

01:04 So moles of carbon that will be the mass 38 .7 grams divided by the molar mass of carbon and we get 3 .222.

01:18 Then we will find out moles of hydrogen that will be mass 9 .7 grams hydrogen divided by molar mass of hydrogen 1 .01 grams per mole and we get 9 .604 and then moles of oxygen mass is 51 .6 grams divided by the molar mass 16 grams per mole and we get 3 .22.

01:52 Now the ratio of moles of carbon to hydrogen to oxygen that is equal to 3 .222 to 9 .604 to 3 .225 and to get the whole number ratio we will divide each number by the smallest number that is divided by 3 .222, 9 .604 divided by 3 .222 and 3 .225 divided by 3 .222 and we get 1 to 3 to 1.

02:41 So, this is the smallest whole number ratio of moles of carbon to hydrogen to oxygen.

02:48 So we will find out the empirical formula of the compound, empirical formula of ethylene glycol and that will be ch3o because the ratio is 1 to 3 to 1...

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