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siniylev [52]
3 years ago
5

6.7 mL of a ptassium chlorid solution was added to a 54.730 gevaporating dish. The combination weight 61.945 g. Afterevaporation

the dish contents weight 55.428 g.
a. What was the mass percent of potassium chloride in thesolution?
b. If the actual mass percent of the potassium in the abovesolution was 10.00%, what was the percentage error of the abovemeasurment?
c. Why was the evaporation used to determine the masspercentage of potassium cloride in the solution rather than thefiltration or recrystallization? Explain.
Chemistry
1 answer:
Semmy [17]3 years ago
3 0

Explanation:

A.

Mass of evaporation dish + solution of KCl = mass of dish + mass of solution of KCl

61.945 = 54.73 + mass of KCl solution

= 7.215 g

Mass of evaporation dish + dry KCl = mass of dish + mass of dry KCl

55.428 = 54.73 + mass of dry KCl

= 0.698 g.

% Mass of KCl = mass of dry KCl/mass of KCl solution * 100

= 0.698/7.215 * 100

= 9.67%

B.

At 10%, mass = 0.7215 g

Change in error = 0.7215 - 0.698

= 0.0235 g

% error = change in error/actual mass at 10% * 100

= 0.0235/0.7215 * 100

= 3.26 %

C.

In evaporation, KCl does not decompose on heating. In filtration, there needs to be a heterogeneous solution(particles or suspension of KCl present) and it is not suitable for soluble salts while recrystallisation is mainly a purification process for solution and KCl is equally soluble in cold and hot water.

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Identify the conjugate acid/base pairs in each of the following equations:
Valentin [98]

Answer:

(a) Pair 1: H₂S and HS⁻

    Pair 2: NH₃ and NH₄⁺

(b) Pair 1: HSO₄⁻ and SO₄⁻

    Pair 2: NH₃ and NH₄⁺

(c) Pair 1: HBr and Br⁻

    Pair 2: CH₃O⁻ and CH₃OH

(d)  Pair 1: HNO₃ and NO₃⁻

     Pair 2: H₃O⁺

Explanation:

When an acid loses its proton (H⁺), a conjugate base is produced.

When a base accepts a proton (H⁺), it forms a conjugate acid.

(a) H₂S is an acid. When it loses a proton, it forms the conjugate base HS⁻.

    NH₃ is a base. When NH₃ gains a proton, it forms the conjugate acid NH₄⁺

(b) The acid HSO₄⁻ loses a H⁺ ion and forms the conjugate base SO₄²⁻.

     The base NH₃ accepts a H⁺ ion to form the conjugate acid NH₄⁺.

(c) HBr is an acid. When loses the H⁺ ion, it forms the conjugate base Br⁻.

   CH₃O⁻ accepts a H⁺ ion to form the conjugate acid CH₃OH.

(d) HNO₃ loses a proton to form the conjugate base NO₃⁻.

    H₂O gains a proton to form the conjugate acid H₃O⁺.

6 0
3 years ago
Once again if anyone could help, I would really appreciate your help! Thank you ❤️
Nikolay [14]

Answer:

D

Explanation:

I explained how to do it on your other problem so look there :)

6 0
3 years ago
25 POINTS!
ryzh [129]

Answer: The Answer is B. Energy can not be created nor destroyed.

Explanation:

4 0
3 years ago
Will medal!!!
hjlf
Δ H reaction = q / n where q: amount of heat released and n is number of moles of substance.
q = m . C . ΔT where:
m = mass of substance (g)
C = Specific heat capacity (4.18)
ΔT = change in temperature = 24.25 - 23.16 = 1.09
q = 1000 x 4.18 x 1.09 = 4556 J = 4.556 kJ
number of moles (n) = Molarity (M) x Volume (L)
                                 = 0.185 M x 0.07 L = 0.01295 mole
Δ H = q / n = - (4.556 kJ / 0.01295 mole) = -351.8 kJ / mol
Note: it is exothermic reaction (-ve sign)  i.e. temperature is raised

5 0
3 years ago
a gas in a container with a fixed volume was originally at a pressure of 317kpa and a temperature of 154k. what is the new press
goldfiish [28.3K]
<h2>Hello!</h2>

The answer is: 4.77atm

<h2>Why?</h2>

Since there's a fixed volume, we can use the the Gay-Lussac's Law which stablish a relation between the pressure and the temperature:

\frac{P}{T}=k

<em>P</em> is the volume of the gas

<em>t</em> is the temperature of the gas

<em>k </em>is the proportionality constant

We also have the following equation:

\frac{P1}{T1}=\frac{P2}{T2}

Where:

P2=\frac{P1*T2}{T1}=\frac{317kPa*235K}{154K}=483.73kPa

We are asked to find the pressure in atm, so we must convert 483.73kPa to atm:

1kPa=0.009869atm

Then,

483.733kPa*\frac{0.009869atm}{1kPa}=4.77atm

Have a nice day!

8 0
3 years ago
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