Chemistry, 05.05.2020 01:29 Natalierg05

What is the molarity of a solution of KCl if 1500. mL contains 149.2 grams of KCl? (Atomic mass of K = 39.10 g/mol and Cl = 35.45 g/mol)

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Answer from: skdkdksks

The molarity of a solution of KCl is 1.33 $\frac{moles}{L}$

Explanation:

The Molarity (M) or Molar Concentration is the number of moles of solute that are dissolved in a given volume. In other words, the molarity is the number of moles of solute per liter of solution.

Molarity is determined by the expression:

$Molarity(M)=\frac{number of moles}{volume}$

Molarity is expressed in units ( $\frac{moles}{liter}$ ).

So in this case you need to know the number of moles. For that you must know the molar mass of KCl. You know:

K= 39.10 g/molCl= 35.45 g/mol

So the molar mass of KCl is: KCl= 39.10 g/mol + 35.45 g/mol= 74.55 g/mol

Then the following rule of three applies: if 74.55 grams of KCl are in 1 mole, 149.2 grams of KCl in how many moles will they be?

$moles=\frac{149.2 g*1 moles}{74.55 g}$

moles= 2

So you know:

number of moles= 2volume= 1500 mL=1.5 L (being 1 L=1000 mL)

Replacing in the definition of molarity:

$Molarity =\frac{2 moles}{1.5 L}$

Solving:

Molarity= 1.33 $\frac{moles}{L}$

The molarity of a solution of KCl is 1.33 $\frac{moles}{L}$

Answer from: Quest

the millers tale is the answer.

Answer from: Quest

remember that hf is only the energy of one photon. not two. not three. one. 1) 5.12 * 10^3 photons find the energy of one photon, then determine how many photons are needed to reach the sensitivity. e = hf = (6.626 * 10^-34 js)(5.95 * 10^19 hz) = 3.94247 * 10^-14 j per photon (2.02 * 10^-10 j) / (3.94247 * 10^-14 j/photon) = 5123.69149 photons round to three sig figs. 2) 5.77 * 10^-17 j energy of pulse = energy per photon * number of photons = hfn = (6.626 * 10^-34 js)(1.66 * 10^13 hz)(5250) = 5.774559 * 10^-17 j round to three sig figs. 3) 4.07 * 10^8 kj/mol 10^12 pm = 1 m c = fλ f = c/λ e = hf = hc/λ = [(6.626 * 10^-34 js)(3.00 * 10^8 m/s) / (2.94 * 10^-12 m)](1 kj/1000 j)(6.02 * 10^23 photons/mol) = 40702571.4 kj/mol round to three sig figs. 4) 9.94 * 10^-1 m e = hc/λ λ = hc / e = (6.626 * 10^-34 js)(3.00 * 10^8 m/s) / (2.00 * 10^-25 j) = 0.9939 m round to three sig figs. 5) 9.06 * 10^3 photons energy of pulse = energy per photon * number of photons number of photons = energy of pulse / energy per photon = energy of pulse / (hf) = (3.87 * 10^-13 j) / [(6.626 * 10^-34 js)(6.45 * 10^16 hz)] = 9055.23695 photons round to three sig figs. 6) 2.78 * 10^-15 j this is problem 1, except in reverse. sensitivity = minumum number of photons * energy per photon = (5930)(6.626 * 10^-34 js)(7.077 * 10^14 hz) = 2.78070758 × 10^-15 j round to three sig figs.

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What is the molarity of a solution of KCl if 1500. mL contains 149.2 grams of KCl? (Atomic mass of K...

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