The mole fraction of HCl in 20 percent aqueous solution is 0.21.
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The mole fraction of HCl in a 20% aqueous solution can be calculated by converting the percentage to a molarity concentration. Assuming the density of the solution is 1 g/mL, a 20% solution means 20g of HCl in 100g of solution. If the molar mass of HCl is 36.5 g/mol, we can calculate the molarity and then use it to find the mole fraction of HCl in the solution.
To find the mole fraction of HCl in the solution, we first need to calculate the molar mass of HCl (H=1g/mol, Cl=35.5g/mol). Then, determine the number of moles of HCl in 100g of the solution. Finally, calculate the mole fraction of HCl by dividing the moles of HCl by the total moles of solute and solvent in the solution.
To calculate the mass percent of benzene in the solution, we first need to convert the mole fraction of benzene to mass fraction using the molecular weights of benzene and toluene. Then, we can use the formula: Mass percent = (mass fraction of benzene / total mass of solution) x 100 Given the mole fraction of benzene as 0.40, we can use this information to determine the mass fraction and then calculate the mass percent of benzene in the solution.
First, calculate the volume percentages of ethanol and water in the solution. Since we know the density of both solvents, convert the percentages to mass (using density and volume). Then calculate the mole fraction of ethanol by dividing the moles of ethanol by the total moles of all components in the solution. Finally, calculate molality using the moles of solute (ethanol) and the mass of the solvent (water).
You would need to add 18.75g of solid NaOH to the 750g of aqueous solution to obtain a 2.5% NaOH solution by mass.
percent concentration = (mass of solute/volume of solution) X 100 To solve for mass of solute, mass of solute = (percent concentration X volume of solution)/100 So, mass of solute = (10% X 100mL)/100 = 10g