Hydrochloric acid is used to produce fertilizers and dyes, to pickle and clean metal products, and as a reagent in the photograp
1 answer:
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The number of silicon atoms that are in this sample is: B.
<u>Given the following data:</u>
- Mass of silicon = 98.3 grams
<u>Scientific data:</u>
- Avogadro's number =
- Molar mass of silicon = 28.09 g/mol.
To determine the number of silicon atoms that are in this sample:
First of all, we would determine the number of moles contained in 98.3 grams of silicon.
Number of moles = 3.4995 moles
<u>By stoichiometry:</u>
1 mole of silicon = atoms
3.4995 moles of silicon = X atoms
Cross-multiplying, we have:
Read more on atoms here: brainly.com/question/10614569
Explanation:
It is given that mass is 11 kg. Convert mass into grams as follows.
= 11000 g (as 1 kg = 1000 g)
Now, calculate the number of moles as follows.
No. of moles =
=
= 211.54 mol
For , 3 moles of electrons are required
Hence,
= 634.62 mol
As 1 mol of electrons contain 96500 C of charge. Therefore, charge carried by 634.62 mol of electrons will be calculated as follows.
Q =
= of charge
We know that relation between charge, current and time is as follows.
Q =
Current is given as 41.5 A and charge is calculated as . Therefore, calculate the time as follows.
Q =
t =
As there are 3600 seconds in one 1 hour. Therefore, converting into hours as follows.
= 4.09 hr
Thus, we can conclude that it takes 4.09 hours to plate 11.0 kg of chromium onto the cathode if the current passed through the cell is held constant at 41.5 A.
Answer:
25,3mL of 0,450M HCl are the maximum volume you can add to the buffer.
Explanation:
The maximum buffer capacity that you can have with HCOOH-HCOO⁻ is when the acid and its conjugate base are in the same proportions, that means [HCOOH] = 0,090M and [HCOO⁻] = 0,090M.
In moles: 0,155L×0,090M = 0,01395 moles
Hendersson-Hasselbalch equation for this system is:
pH = 3,74 + log₁₀ [HCOO⁻] /[HCOOH]
The pH of this buffer is equal to pka = 3,74.
A buffer lost is buffering capacity when pH is pka-1 or pka+1. Under addition of HCl the buffer will lost is buffering capacity when pH = 2,74. Using Henderson-Hasselbalch equation:
2,74 = 3,74 + log₁₀ [HCOO⁻] /[HCOOH]
0,1 = [HCOO⁻] /[HCOOH] <em>(1)</em>
The reaction of HCl with HCOO⁻ is:
HCOO⁻ + HCl → HCOOH + Cl⁻
Using this reaction and moles of formic/formiate buffer:
0,1 = [0,01395-x] / [0,01395+x]
Being x the moles of HCl added in the reaction.
0,001395+0,1x = 0,01395 - x
1,1x = 0,012555
x = 0,0114 moles of HCl you need to add.
As the concentration of the HCl solution is 0,450M
0,0114 mol × = 0,0253L ≡ <em>25,3 mL </em>that are the maximum volume you can add.
I hope it helps!