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2 years ago

KCl is an ionic salt with a formula weight of 74.54 g/mole.

Chemistry

1 answer:

aalyn [17]2 years ago

5 0

Answer:

mass of water = 958 g = 0.958 kg

m = 1.48 mol/kg

Explanation:

Given:

MM(KCl)= 74.54 g/mol

M= 1.417 mol/L

density of solution= 1064 g/L

To calculate the mass of water in 1 L of solution, first we have to multiply the molarity of the solution (M) by the molecular weight of KCl (MM):

1.417 mol/L x 74.54 g/mol = 105.62 g/L

As the density of the solution is 1064 g/L, we know that 1 L is equal to 1064 g. So, we have 105.62 g of KCl in 1064 g of solution. The mass of water will be the difference between the mass of solution and the mass of solute:

mass of water (g) = 1064 g - 105.6 g = 958.4 g

mass of water (kg)= 958.4 g x 1 kg/1000 g = 0.958 kg

To determine the molality (m):

m = moles of KCl/kg water

m = 1.417 moles/0.958 kg = 1.479 mol/kg

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5. A penny weighs about 2.5 g. How many moles of pennies would be required to equal the mass of the moon (7.3x10^24 kg)

schepotkina [342]

5. 1.16 x $10^{26}$ moles moles of pennies would be required to equal the mass of the moon.

6. 12.86 moles of ethanol are in a 750 ml bottle of vodka.

Explanation:

5 .Data given:

mass of penny = 2.5 grams

atomic mass of penny = 62.93 grams/mole

moles present in mass of the moon given as = 7.3 x $10^{24}$ kg

number of moles = $\frac{mass}{atomic mass of 1 mole}$

number of moles = $\frac{2.5}{62.93}$

0.039 moles of penny is present in 2.5 grams

0.039 moles of penny in 2.5 grams of it

so, x moles in 7.3 X $10^{27}$ grams

$\frac{0.039}{2.5} =\frac{x}{7.3 X 10^{27} }$

x = 1.16 x $10^{26}$ moles

so when the mass of the penny given is equal to the mass of moon, number of moles of penny present is 1.1 x $10^{26}$ .

Given:

vodka = 40% ethanol

volume of vodka bottle = 750 ml

moles of ethanol =?

density of ethanol =0.79 g/ml

atomic mass of ethanol = 46.07 grams/mole

so, from the density of ethanol given we can calculate how much ethanol is present in the solution.

density = $\frac{mass}{volume}$

density x volume = mass

0.79 x 750 = 592.5 grams

number of moles = $\frac{mass}{atomic mass of 1 mole}$

number of moles of ethanol = $\frac{592.5}{46.07}$

= 12.86 moles of ethanol

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2 years ago

A reaction that is NOT thermodynamically favored at low temperatures can become thermodynamically favored at high temperatures

Rom4ik [11]

Explanation:

Its gonna be D

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2 years ago

15 POINTS PLEASE HELP What volume of water must be added to 35mL of 2.6m KCl to reduce its concentration to 1.2m? Please explain

BartSMP [9]

First, find the volume the solution needs to be diluted to in order to have the desired molarity:
You have to use the equation M₁V₁=M₂V₂ when ever dealing with dilutions.

M₁=the starting concentration of the solution (in this case 2.6M)
V₁=the starting volume of the solution (in this case 0.035L)
M₂=the concentration we want to dilute to (in this case 1.2M)
V₂=the volume of solution needed for the dilution (not given)

Explaining the reasoning behind the above equation:
MV=moles of solute (in this case KCl) because molarity is the moles of solute per Liter of solution so by multiplying the molarity by the volume you are left with the moles of solute. The moles of solute is a constant since by adding solvent (in this case water) the amount of solute does not change. That means that M₁V₁=moles of solute=M₂V₂ and that relationship will always be true in any dilution.

Solving for the above equation:
V₂=M₁V₁/M₂
V₂=(2.6M×0.035L)/1.2M
V₂=0.0758 L
That means that the solution needs to be diluted to 75.8mL to have a final concentration of 1.2M.

Second, Finding the amount of water needed to be added:
Since we know that the volume of the solution was originally 35mL and needed to be diluted to 75.8mL to reach the desired molarity, to find the amount of solvent needed to be added all you do is V₂-V₁ since the difference in the starting volume and final volume is equal to the volume of solvent added.
75.8mL-35mL=40.8mL
40.8mL of water needs to be added

I hope this helps. Let me know if anything is unclear.
Good luck on your quiz!

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Murrr4er [49]

Answer: think a

Explanation:

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1 year ago

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