1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
mash [69]
3 years ago
12

As part of a soil analysis on a plot of land, a scientist wants to determine the ammonium content using gravimetric analysis wit

h sodium tetraphenylborate, Na+B(C6H5)−4. Unfortunately, the amount of potassium, which also precipitates with sodium tetraphenylborate, is non‑negligible and must be accounted for in the analysis. Assume that all potassium in the soil is present as K2CO3 and all ammonium is present as NH4Cl.
A 5.025 g soil sample was dissolved to give 0.500 L of solution. A 100.0 mL aliquot was acidified and excess sodium tetraphenylborate was added to precipitate both K+ K + and NH+4 ions completely.
Compound Formula mass
B(C6H5)−4+K+⟶KB(C6H5)4(s) KB(C6H5)4 358.33 g/mol
B(C6H5)−4+NH+4⟶NH4B(C6H5)4(s) NH4B(C6H5)4 337.27 g/mol
K2CO3 138.21 g/mol
NH4Cl 53.492 g/mol
The resulting precipitate amounted to 0.277 g. A new 200.0 mL aliquot of the original solution was made alkaline and heated to remove all of the NH+4 as NH3. The resulting solution was then acidified, and excess sodium tetraphenylborate was added to give 0.105 g of precipitate.
Find the mass percentages of NH4Cl and K2CO3 in the original solid.
______ %NH4CL
______ %K2CO3
Chemistry
1 answer:
jeka943 years ago
7 0

Answer:

Mass percentage of NH₄Cl = 3.54%

Mass percentage of K₂CO₃ = 1.01%

Explanation:

If a 200.0 mL aliquot produced  0.105 g of KB(C₆H₅)₄, then a 100.0 mL aliquot would produce 1/2 * 0.105 g = 0.0525 g of KB(C₆H₅)₄.

Therefore, mass of NH₄B(C₆H₅)₄ in the 100.0 ml aliquot = (0.277 - 0.0525)g = 0.2245 g

Number of moles of NH₄B(C₆H₅)₄ in 0.2245 g = 0.2245 g/ 337.27 g/mol = 0.0006656 moles

In 500 ml solution, number of moles present = 0.0006656 * 500/100 = 0.003328 moles.

From equation of the reaction; mole ratio of  NH₄⁺ and NH₄B(C₆H₅)₄ = 1:1

Similarly, mole ratio of  NH₄⁺ and NH₄Cl = 1:1

Therefore, moles of NH₄Cl in 500 ml sample = 0.003328 moles

Mass of NH₄Cl  = 0.003328 mol * 53.492 g/mol = 0.178 g

Mass percentage of NH₄Cl = (0.178/5.025) * 100% = 3.54%

Number of moles of KB(C₆H₅)₄ in 0.105 g (precipitated from 200.0 ml aliquot) = 0.105 g/ 358.33 g/mol = 0.000293 moles

In 500 ml solution, number of moles present = 0.000293 * 500/200 = 0.0007326 moles.

From equation of the reaction; mole ratio of  K⁺ and KB(C₆H₅)₄ = 1:1

Similarly, mole ratio of  K⁺ and K₂CO₃ = 2:1

Therefore, moles of K₂CO₃ in 500 ml sample = 0.0007326/2 moles =  0.0003663 moles

Mass of  K₂CO₃ = 0.0003663 mol * 138.21 g/mol = 0.05063 g

Mass percentage of K₂CO₃ = (0.05063/5.025) * 100% = 1.01%

You might be interested in
have you ever been swimming and noticed some areas in the water are colder and other are warmer? why do you think this happens
timama [110]
Maybe because someone hasn't been swimming on tht side bacause the water changes it's tempurture from your body heat or maybe because it isnt any sun out

6 0
3 years ago
*<br> What is the volume, in liters, of 12.0 kg of H2 at STP?
neonofarm [45]

Answer:

According to Avogadro's law, the volume of one mole of any gas at Standard Temperature and Pressure (STP = 273 K and 1 atm) is 22.4 L. Two important Gas Laws are required in order to convert the experimentally determined volume of hydrogen gas to that at STP. 1.

Explanation:

internet keep searching

6 0
3 years ago
What are the five main chemical compounds of life
anygoal [31]
Carbohydrates,Lipids,Proteins,Nucleic acids,<span>Organic Compounds</span>

4 0
3 years ago
Balance the equation in the box. Click in the answer box to activate the palette. N2(g) + H2(g) → NH3(g)
lesantik [10]

Answer:

N2(g) + 3H2(g) → 2 NH3(g)

Explanation:

N2(g) + H2(g) → NH3(g)

We start equaling the number of N atoms in both sides multiplying by 2 the NH3.

N2(g) + H2(g) → 2 NH3(g)

So we equals the H atoms (there are six in products sites)

N2(g) + 3 H2(g) → 2 NH3(g)

7 0
3 years ago
7. Halfway through a cross country meet, a
kondor19780726 [428]

Answer:

3m/s

Explanation:

Data obtained from the question include:

Initial speed (s1) = 4 m/s

Final speed (S2) = 7m/s

Change in speed (ΔS)

ΔS = s2 — s1

ΔS = 7 — 4

ΔS = 3m/s

Therefore, the change in speed is 3m/s

7 0
3 years ago
Other questions:
  • What do all the atomic models have in common?
    13·1 answer
  • Crossover formula of potassium oxide.
    13·1 answer
  • What are the products formed when zinc reacts to dilute hydrochloride acid
    12·2 answers
  • If a car travels 60 miles in 3 hours, what is the car’s speed?
    13·2 answers
  • There are exaclty 640 acres in one square mile. How many square meters are in 2.2 acres?
    8·1 answer
  • How are real Gases Different from ideal Gases?
    11·1 answer
  • What are the two components of a solution
    10·1 answer
  • Help ASAP no links or I’m reporting only answer if you are confident and if you are correct
    8·1 answer
  • The volume of a metal rod was determined to be 38.6 mL. Its
    12·1 answer
  • Solve 21 and 22 please
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!