What is the molality of a solution that contains 418.8 g HCl in 4.62 kg water? Select one:
O a 2.49
Ob. 0.00249
Oc. 15.3
Od.4.19e5

a 2.49

Explanation:

Molality is a measure of concentration of solution which describes the number of moles of solute per kilograms of the solvent.

Molality (M) = number of moles of solute (n) / kg solvent

According to the question; mass of solute (HCl) = 418.8g, mass of solvent (water) = 4.62kg

To find the number of moles (n) of solute (HCl), we use; mass (g) / molar mass (g/mol)

Molar mass of HCl = 1 + 35.5 = 36.5g/mol

Hence, n= 418.8/36.5

n= 11.4739

n= 11.5

Therefore, Molality= 11.5 mol of HCl / 4.62kg of water

M= 11.5/4.62

M= 2.489

Hence, molality of the solution is 2.49

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.