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irinina [24]
3 years ago
13

Commercial grade HCl solutions are typically 39.0% (by mass) HCl in water. Determine the molality of the HCl, if the solution ha

s a density of 1.20 g/mL
Chemistry
1 answer:
marta [7]3 years ago
8 0

Molality of the solution is defined as the number of moles of a substance dissolved divided by the mass of the solvent:

Molality = number of moles / solvent mass

From the concentration of 39% (by mass) of HCl in water, we construct the following  reasoning:

in 100 g solution we have 39 g hydrochloric acid (HCl)

number of moles  = mass / molecular weight

number of moles of HCl = 39 / 36.5 = 1.07 moles

solvent (water) mass = solution mass - hydrochloric acid mass

solvent (water) mass = 100 - 39 = 61 g

Now we can determine the molality:

molality = 1.07 moles / 61 g = 0.018

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Jobisdone [24]
I think it’s 2 hope that helped
4 0
3 years ago
If the container is closed and the ethanol is allowed to reach equilibrium with its vapor, how many grams of liquid ethanol rema
SVETLANKA909090 [29]

Explanation:

Let us assume that the given data is as follows.

        V = 3.10 L,        T = 19^{o}C = (19 + 273)K = 292 K

       P = 40 torr    (1 atm = 760 torr)

So,     P = \frac{40 torr}{760 torr} \times 1 atm

             = 0.053 atm

          n = ?

According to the ideal gas equation, PV = nRT.

Putting the given values into the above equation to calculate the value of n as follows.

                 PV = nRT

   0.053 atm \times 3.10 L = n \times 0.0821 L atm/mol K \times 292 K

                 0.1643 = n \times 23.97

                    n = 6.85 \times 10^{-3}

It is known that molar mass of ethanol is 46 g/mol. Hence, calculate its mass as follows.

               No. of moles = \frac{mass}{\text{molar mass}}

                 6.85 \times 10^{-3} = \frac{mass}{46 g/mol}  

                    mass = 315.1 \times 10^{-3} g

                              = 0.315 g

Thus, we can conclude that the mass of liquid ethanol is 0.315 g.

4 0
3 years ago
To grow or reach the next stage in a life cycle is to develop.
gogolik [260]

Answer:

It's obviously true

Explanation:

As we have evolved over the years we have become more advanced

5 0
3 years ago
2 points
Drupady [299]

Answer: The ratio of carbon to bromine atoms  in the molecule is 3:1

Explanation:

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass. It can be decomposed into simpler constituents using chemical reactions.

Chemical formula shows the elements in a compound and the relative proportions of those elements.

The chemical formula given for the compound is C_3H_6BrCl which means the ratio of carbon to bromine atoms is 3: 1.

Thus the ratio of carbon to bromine atoms  in the molecule is 3:1

7 0
3 years ago
A) Calculate the osmotic pressure difference between seawater and fresh water. For simplicity, assume thatall the dissolved salt
never [62]

Answer:

a)  Δπ = 1.264 atm

b) W = 128 joules

c)  ΔH >> W  ( a factor greater than 17,000 )

Explanation:

a) The osmotic pressure, π , is determined by :

π = nRT/V, where n= moles of solute

                          R= 0.0821 Latm/kmol

                          T = 300 K

calling π(sw) osmotic pressure for  for sea water and π (fw) for fresh water,

salinity of sea water = 3.5 g / 1L water   (assuming only NaCl for the salts)

salinity of fresh water = 0.5 parts per thousand (range: 0- 0.5 ppt)

πsw = (3.5 g/58.44 g/mol) (0.0821 Latm/Kmol) (300 K ) /1 L = 1.475 atm

πfw = (0.5 g/58.44 g/mol) (0.0821 Latm/Kmol) (300 K ) /1 L = 0.211 atm

d water = 1 g/cm³

Δ π = (1.475 - 0.211) = 1.264 atm

b) W = Δπ V = 1.426 atm x 1L = 1.43 L-atm

1 L-atm = 101.33 j

W =  101.33 j/ Latm x  1.43 Latm = 128 joules

c) ΔH = Q₁ + nΔH vap, where

            Q₁  = heat required to bring the solution from 300 K to boiling, 373 K

            ΔH vap = heat of vaporization

Q = mCΔT = 1000 g x 4.186 j x 73 K = 305.6 j = 0.3056 kj

ΔH vap = (1000 g/ 18 g/mol ) 40.7 kj/mol = 2,261 kj

ΔH =  0.3056 kj + 2,261 kj = 2,261.3 kj

Note = Q << ΔH vap and we could have neglected it.

This result shows why nobody talks about evaporation of sea water to produce fresh water ΔH >> W

6 0
3 years ago
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