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valkas [14]
3 years ago
11

HELP PLEASE 100 points!!!

Chemistry
2 answers:
Helga [31]3 years ago
7 0

Answer:

The answer B

.

Explanation:

djyliett [7]3 years ago
3 0

Answer:

by the looks of it the answer you have is correct

Explanation:

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How many grams of a stock solution that is 87.5 percent H2SO4 by mass would be needed to make 275 grams of a 55.0 percent by mas
Mandarinka [93]
<span>We're diluting the first solution to make the second solution. This means both solutions will contain the same amount of H2SO4 (it's the concentration of it that changes). If you look at it this way, it's easy to find the unknown mass. Call this unknown mass m. m * 0.875 = 275 g * 0.55 --> m = 173 g What I'm saying here is 87.5% of the mass of the first solution needs to be the same as 55% of the mass of the second solution, because you're using the same amount of H2SO4 in both.

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3 years ago
A scientist finds that a sample of matter contains three types of atoms. The sample can be any of the following, except:
GrogVix [38]

Answer:

The correct answer is C. element

Explanation:

The sample cannot be an element because an element - or <em>elemental substance</em> - cannot be decomposed into simpler substances. Thus, it cannot be composed by differents types of atoms. For example, an element is carbon (C).

As the sample contains <u>three types of atoms</u>, it can be a compound, a molecule or a mixture, because they can be composed by different types of atoms - of different chemical elements. For example, the sample could contain the element carbon (C) combined with other elements, for example oxygen (O) or hydrogen (H), amoing others.

6 0
3 years ago
Add oxidation numbers to the following reaction: 2 H3PO4 (aq) + 2 Cr(s) → 2 CrPO4 (aq) + 3 H2(g). Identify the atom that is oxid
rewona [7]

The atom that is oxidized : Cr

The oxidizing agent : H₃PO₄

<h3>Further explanation</h3>

Reaction

2 H₃PO₄ (aq) + 2Cr(s) → 2 CrPO₄ (aq) + 3H₂(g)

Atoms undergoing a reduction reaction (decrease in oxidation number) and an oxidation reaction (increase in oxidation number)

  • Reduction (+1 to 0)

H⁺(in H₃PO₄) =+1

H₂=0

  • Oxidation (0 to +3)

Cr = 0

Cr³⁺(in CrPO₄ )

the oxidizing agent.⇒which undergoes a reduction reaction and oxidizes another compound/element : H₃PO₄

3 0
3 years ago
Which of the following should be classified as a mixture? water air iron helium
Evgesh-ka [11]
Air is a mixture because it is made up of many constituents like oxygen, argon etc. it can be physically separated by fractional distillation. it doesnt have a formula unlike compounds and elements. its composition varies differently with its constituents.
5 0
3 years ago
Read 2 more answers
<img src="https://tex.z-dn.net/?f=H_2PO_4%5E-%28aq%29%20%5Crightarrow%20H%5E%2B%28aq%29%20%2B%20HPO_4%5E%7B2-%7D%28aq%29" id="Te
klasskru [66]

Answer:

The pH of the buffer solution = 8.05

Explanation:

Using the Henderson - Hasselbalch equation;

pH = pKa₂ + log ( [HPO₄²-]/[H₂PO4⁻]

where pKa₂ = -log (Ka₂) = -log ( 6.1 * 10⁻⁸) = 7.21

Concentration of OH⁻ added = 0.069 M (i.e. 0.069 mol/L)

[H₂PO4⁻] after addition of OH⁻ = 0.165 - 0.069 = 0.096 M

[HPO₄²-] after addition of OH⁻ = 0.594 + 0.069 = 0.663 M

Therefore,

pH = 7.21 + log (0.663 / 0.096)

pH = 7.21 + 0.84

pH = 8.05

4 0
3 years ago
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