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3 years ago

9

Please help I’m torn between A and B. I’ve asked many and people say A, but I asked my science teacher and she said B. And also

I’ve researched and on answers.com also says Water is the better insulator..but idk I’m conflicted! APEX

1 answer:

Vladimir79 [104]3 years ago

8 0

Just choose one of them. Getting one question wrong isn't the end of the world.

I suggest water.

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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

10. Air is a homogenous mixture of gases. Oxygen is 20% by volume of air typically. What

raketka [301]

Answer:

893 moles

Explanation:

An ideal gas at STP occupies 22.4 liters. Calculating Oxygen as if it were an ideal gas there are . 893 moles of Oxygen in 20.0 liters.

3 0

3 years ago

The air in a 2 L balloon at 0.998 atm and 34.0 °C. What will be its pressure if it is brought to a higher altitude where it now

Phantasy [73]

Answer: 0.529 atm

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

where,

$P_1$ = initial pressure of gas = 0.998 atm

$P_2$ = final pressure of gas = ?

$V_1$ = initial volume of gas = 2 L

$V_2$ = final volume of gas = 3.5 L

$T_1$ = initial temperature of gas = $34.0^oC=273+34.0=307.0K$

$T_2$ = final temperature of gas = $12.0^oC=273+12.0=285.0K$

Now put all the given values in the above equation, we get:

$\frac{0.998\times 2}{307.0K}=\frac{P_2\times 3.5}{285.0K}$

$P_2=0.529atm$

Thus the pressure if it is brought to a higher altitude where it now occupies 3.5 L and is at 12.0 °C is 0.529 atm

4 0

4 years ago

What happens at night?

Alex

Warm air other the ocean moves onshore I think

7 0

3 years ago

Hydrogen ions cannot exist alone but they exist after combining with water molecules true or false

juin [17]

True because hydrogen ions combines with h2o to make hydronium ion, so in a sense h2o is acting like a base.

4 0

3 years ago