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aleksley [76]
3 years ago
15

What is always included in a comparative investigation?

Chemistry
2 answers:
Salsk061 [2.6K]3 years ago
4 0
These all seem right
Strike441 [17]3 years ago
3 0

Answer:

answer b

Explanation:

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When of glycine are dissolved in of a certain mystery liquid , the freezing point of the solution is lower than the freezing poi
Nesterboy [21]

The given question is incomplete. The complete question is:

When 282. g of glycine (C2H5NO2) are dissolved in 950. g of a certain mystery liquid X, the freezing point of the solution is 8.2C lower than the freezing point of pure X. On the other hand, when 282. g of ammonium chloride are dissolved in the same mass of X, the freezing point of the solution is 20.0C lower than the freezing point of pure X. Calculate the van't Hoff factor for ammonium chloride in X.

Answer:  the van't Hoff factor for ammonium chloride is 1.74

Explanation:

Depression in freezing point is given by:

\Delta T_f=i\times K_f\times m

\Delta T_f=T_f^0-T_f=8.2^0C = Depression in freezing point  

K_f = freezing point constant = ?

i = 1 ( for non electrolyte)

m= molality

8.2^0C=1\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}

Weight of solvent (X)= 950 g = 0.95 kg

Molar mass of solute (glycine) = 75.07 g/mol

Mass of solute (glycine) = 282 g

8.2^0C=1\times K_f\times \frac{282g}{75.07g/mol\times 0.95kg}

K_f=2.07

ii) 20.0^0C=i\times \times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}

Weight of solvent (X)= 950 g = 0.95 kg

Molar mass of solute (ammonium chloride) = 53.49 g/mol

Mass of solute (ammonium chloride) = 282 g

20.0^0C=i\times 2.07\times \frac{282g}{53.49g/mol\times 0.95kg}

i=1.74

Thus the van't Hoff factor for ammonium chloride is 1.74

4 0
3 years ago
When a 13.0g sample of NaOH(s) dissolves in 400.0 mL water in a coffee cup calorimeter, the temperature of the water changes fro
Tom [10]

Answer:440.154j

Explanation:

H=mcΔT

H= 13*4.18*8.1

H=440.154j

4 0
3 years ago
What percentage of water do we use for flushing our toilets?.
solong [7]

Answer:

30%

Explanation:

4 0
2 years ago
If an atom has nine protons, eight neutrons and ten electrons what is its charge?
sp2606 [1]
 THE CHARGE IS NEGATIVE BECAUSE THE  NUMBER OF ELECTRON IS MORE THAN THE NUMBER OF PROTON
8 0
3 years ago
Read 2 more answers
Suppose that you have a 60.0% solution of NaOH. How many milliliters of water must be added to 30.0 mL of this solution to prepa
defon

Answer:

  • <u>21.4 ml (second choice)</u>

Explanation:

<u>1) Data:</u>

a) C₁ = 60.0% (initial solution)

b) V₁ = 30.0 ml (initial solution)

c) C₂ = 0% (pure water)

d) V₂ = ? (pure water)

e) C₃ = 35.0% (final concentration)

<u>2) Formula:</u>

  • C₁V₁ + C₂V₂ = C₃V₃
  • V₁ + V₂ = V₃ (assuming volume addtivity)

<u>3) Solution:</u>

<u />

a) Substitute values in the first formula:

  • 60.0% × 30 ml + 0 = 35% (30 ml + V₂)

b) Solve the equation (units are supressed just to manipulate the terms)

  • 18 = 10.5 + 0.35V₂

  • 0.35V₂ = 18 - 10.5 = 7.5

  • V₂ = 7.5 / 0.35 = 21.4 ml ← answer    
3 0
4 years ago
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