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
Kobotan [32]
3 years ago
15

You want to determine the protein content in milk with the Kjeldahl method. You take 100 g whole milk and use 100 mL of 0.5 M hy

drochloric acid to collect ammonia. You needed 34.50 mL of 0.3512 M NaOH for the back-titration. Calculate the percentage of protein in the sample where CP = 6.38 (that is % protein = CP x %N).
Chemistry
1 answer:
stepladder [879]3 years ago
6 0

Answer:

3.38%

Explanation:

Given that;

the mass of the whole milk sample = 100 g

volume of HCl = 100 mL = 0.1 L

molarity of HCl = 0.5 M

volume of NaOH = 34.50 mL = 0.0345 L

molarity of NaOH = 0.3512 M

Since we knew the molarity and volume of both HCl and NaOH; we can calculate their corresponding number of moles present.

So, number of moles of HCl = molarity of HCl × volume of HCl

number of moles of HCl = 0.5 M ×  0.100 mL

                                        = 0.05 mole

number of moles of NaOH = Molarity of NaOH ×  Volume of NaOH

number of moles of NaOH = 0.3512 M ×  0.0345 L

                                            = 0.012 mole

From the question, we can deduce that the number of HCl that is consumed by NH₃ is equal to the number of moles of HCl that is consumed by NaOH.

SO, number of moles of HCl consumed by NH₃ = Total moles of HCl - moles of HCl consumed by NaOH

= 0.05 mole - 0.012 mole

= 0.038 mole

However, to determine the mole of NH₃ present , we have:

number of moles of NH₃ present = number of moles of HCl consumed by NH₃  = 0.038

∴ the mass of Nitrogen with the molecular weight (14.0 g/mol) = 0.038 moles × 14.0 g/mol

= 0.530 g

Now, the percentage of Nitrogen can be calculated as;

percentage of nitrogen =\frac{mass of nitrogen}{mass of the whole milk sample} *100

percentage of nitrogen =\frac{0.530g}{100g} *100

percentage of nitrogen =0.530%%

the percentage of protein in the sample = CP × %age of N

where CP is given as 6.38

∴ the percentage of protein in the sample = 6.38 ×  0.530%

the percentage of protein in the sample = 3.3814%

the percentage of protein in the sample = 3.38%

You might be interested in
Find energy is the wavelength is 5.2x10^-7m (Show work)
RoseWind [281]

Answer:

E = 3.825×10⁻¹⁹ J

Explanation:

Wavelength of photon = 5.2 ×10⁻⁷m

Energy of photon = ?

Solution:

Formula:

E = hc/λ

h = plancks constant = 6.63×10⁻³⁴ Js

c = speed of wave = 3×10⁸ m/s

by putting values,

E = 6.63×10⁻³⁴ Js ×3×10⁸ m/s / 5.2 ×10⁻⁷m

E = 19.89×10⁻²⁶ J.m / 5.2 ×10⁻⁷m

E = 3.825×10⁻¹⁹ J

4 0
3 years ago
How many degrees is the earth tilted on its axis
kiruha [24]

Answer:

23.5 degrees

Explanation:

Today, the Earth's axis is tilted 23.5 degrees from the plane of its orbit around the sun. But this tilt changes. During a cycle that averages about 40,000 years, the tilt of the axis varies between 22.1 and 24.5 degrees. Because this tilt changes, the seasons as we know them can become exaggerated.

4 0
3 years ago
Read 2 more answers
Which book has kinetic energy
bekas [8.4K]
Where is the picture
3 0
3 years ago
True or False. Star gazing is a pretty popular hobby in today's world.
ValentinkaMS [17]

Answer:

yes (true)

Explanation:

Star gazing has started to become a more popular hobby in todays world due to the pandemic

7 0
3 years ago
Read 2 more answers
1. Find your
bogdanovich [222]

Answer:

you can identify the properties of an element by studying its_____ on the ... between metals and nonmetals on the periodic table are the _____ which have ...

Explanation:

5 0
3 years ago
Other questions:
  • A cylinder with a movable piston contains 2.00 g of helium, He, at room temperature. More helium was added to the cylinder and t
    11·1 answer
  • Which element must be present in an organic compound?(1) hydrogen (3) carbon(2) oxygen (4) nitrogen
    10·2 answers
  • What happens to the charges when an ionic compound forms
    9·1 answer
  • How can gravity's role in tectonic plate motion be described
    12·2 answers
  • What is the name of this hydrocarbon?
    10·2 answers
  • A student would like to determine how heating a liquid changes its volume. The student hypothesizes that the liquid will increas
    15·1 answer
  • Weight measures (2 points) how dense an object is. how large an object is. the amount of mass in an object. the effect of gravit
    10·1 answer
  • A 155-L helium balloon is heated from 24.0 C to 38.0 C. What would be its new volume assuming the pressure remains constant?
    14·1 answer
  • How many moles of hydrogen will be produced in this reaction when 34.5 moles of hydrogen iodide are decomposed?
    11·1 answer
  • Explain why the CO2 from your breath had the effect on the pH of water that it did. Explain any anomalies in your experiment.
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!