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leonid [27]
3 years ago
14

What is the molality of a solution containing 125 grams of iodine (I2) and 750 grams of CCl4? A. 1.2 m. . B. 6.57 m. . C. 0.657

m. . D. 0.12 m.
Chemistry
1 answer:
uysha [10]3 years ago
4 0
The answer is <span>C. 0.657 m.
</span>
The molality is the number of moles of solute divided by kilograms of solvent. In a solution, solute the component which is present in lesser amount while solvent is present in greater amount. Thus, I2 is solute, and CCl4 is solvent.

So, first we need to calculate moles of I2:
Atomic mass of iodine: A(I) = 126.9
Molecular mass of iodine: Mr(I2) = 2*A(I) = 2 * 126.9 = 253.8
This means there are 253.8 g of iodine in 1 mole. So, 125 g of iodine will be in how many moles?
253.8 : 1 = 125 : x         ⇒      x = 125/253.8 = 0.493 moles

Now, let's convert amount of CCl4 in kilograms (1 kg = 1000 g):
750 g = 750/1000 kg = 0.75 kg

And now, it's only left to calculate molality of the solution:
numbers of moles of solute/kilograms of solvent = 0.493 moles/0.75 kg = 0.657 m
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Average speed of the trip = 52 km/hr

<h3>Further explanation  </h3>

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Average speed = total distance/total amount of  time ,

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\tt S(speed)=\dfrac{D}{T}

Total distance travelled : 1560 km

Total time : 8 hr + 12 hr + 10 hr = 30 hr

\tt avg.speed=\dfrac{tot~D}{tot~T}\\\\avg.speed=\dfrac{1560}{30}\\\\avg.speed=52~km/hr

7 0
3 years ago
For hydrocyanic acid, HCN, Ka = 4.9 × 10-10. Calculate the pH of 0.20 M NaCN. What is the concentration of HCN in the solution?
gogolik [260]
By using the ICE table :

initial    0.2 M            0           0
change -X                 + X           +X
Equ     (0.2 -X)            X               X

when Ka = (X) (X) / (0.2-X)
so by substitution:

4.9x10^-10 = X^2 / (0.2-X) by solving this equation for X 
∴X ≈ 10^-6
∴[HCN] = 10^-6

and PH = -㏒[H+]
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3 0
3 years ago
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Given the formulas for the ionic compounds, draw the correct ratio of cations to anions (a) BaSO4, (b) CaF2, (c) Mg3N2, (d) K2O.
Karolina [17]

Answer:

A. It formed by barium(Ba+2) ion and sulfate ( SO42- )

B. It is formed by calcium ion (Ca+2) and two fluoride ions (2F-)

C. It is formed by magnesium ion (Mg+2) and nitride ion (N3-)

D. It is formed by two potassium ions (2 K+) and oxide ion(O2-)

3 0
3 years ago
A solution contains 15.27 grams of NaCl in 0.670 kg water at 25 °C. What is the vapor pressure of the solution?
Anvisha [2.4K]

Answer:

The vapor pressure of the solution is 23.636 torr

Explanation:

P_{solution} = X_{solvent}*P_{solvent}

Where;

P_{solution is the vapor pressure of the solution

X_{solvent is the mole fraction of the solvent

P_{solvent is the vapor pressure of the pure solvent

Thus,

15.27 g of NaCl = [(15.27)/(58.5)]moles = 0.261 moles of NaCl

0.67 kg of water =  [(0.67*1000)/(18)]moles = 37.222 moles of H₂O

Mole fraction of solvent (water) = (number of moles of water)/(total number of moles present in solution)

Mole fraction of solvent (water) = (37.222)/(37.222+0.261)

Mole fraction of solvent (water) = 0.993

<u>Note:</u> the vapor pressure of water at 25°C is 0.0313 atm

Therefore, the vapor pressure of the solution = 0.993 * 0.0313 atm

the vapor pressure of the solution = 0.0311 atm = 23.636 torr

5 0
3 years ago
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When a substance is heated ,the kinetic energy of its molecules
Simora [160]

Answer:

When a substance is heated ,the kinetic energy of its molecules also increase.

Explanation:

K.E is directly proportional to T

5 0
3 years ago
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