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krek1111 [17]
2 years ago
15

Giải thích tại sao chén sấy (hoặc chén nung) dùng chứa tủa phải xử lý cùng với điều kiện xử lý tủa? Thời gian sấy (hoặc nung) bắ

t đầu tính từ thời điểm nào? Giai đoạn sấy (hoặc nung) sau quá trình tạo tủa được gọi là giai đoạn gì? Sản phẩm của giai đoạn này được xử lý bước tiếp theo là gì trước khi thực hiện phép cân? Mục đích của bước xử lý này là gì?
Chemistry
1 answer:
nevsk [136]2 years ago
3 0
Hi how are you doing today Jasmine Jasmine
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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
stepladder [879]

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%

6 0
3 years ago
1. The attraction between the hydrogen atom in one water molecule and the oxygen molecule in another is
Rudik [331]

Answer:

d

ionic bond is formed when there is transfer of electrons and is composed of a positive cation and a negative anion

4 0
3 years ago
What’re the answers?
nikdorinn [45]
7. A conclusion is an educated guess,
or, prediction, about what will happen after the experiment.

8. In observation we use all five senses to gather information.

9. In result we analyze and summarize and ask if the hypothesis was correct.

10. Something that changes or varies in an experiment is called variable.


Ans:
Conclusion
Observation
Results
Variable
3 0
3 years ago
Complete the equation for the dissociation of Na2CO3(aq).Omit water from the equation because it is understood to be present.
ozzi

Answer:

Na2CO3 <==> 2Na^+ + CO3^2-

Explanation:

6 0
2 years ago
What is the number of Valence Electrons for Chlorine?
Alex_Xolod [135]

Answer:

7

Explanation:

6 0
3 years ago
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