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GaryK [48]
3 years ago
13

You are instructed to create 900. mL of a 0.29 M phosphate buffer with a pH of 7.8. You have phosphoric acid and the sodium salt

s NaH2PO4, Na2HPO4, and Na3PO4 available. (Enter all numerical answers to three significant figures.)
H3PO4(s) + H2O(l) <----> H3O+(aq) + H2PO4−(aq) Ka1 = 6.9 ✕ 10−3
H2PO4−(aq) + H2O(l) <----> H3O+(aq) + HPO42−(aq) Ka2 = 6.2 ✕ 10−8
HPO42−(aq) + H2O(l) <----> H3O+(aq) + PO43−(aq) Ka3 = 4.8 ✕ 10−13

Which of the available chemicals will you use for the acid component of your buffer?

A. H3PO4
B. NaH2PO4
C. Na2HPO4
D. Na3PO4

Which of the available chemicals will you use for the base component of your buffer?

A. H3PO4B. NaH2PO4C. Na2HPO4D. Na3PO4
Chemistry
1 answer:
Aleksandr [31]3 years ago
8 0

Answer:

B and C

Explanation:

When we have to do a buffer solution we always have to choose the reaction that has the <u>pKa closer to the desired pH value</u>. When we find the pKa values we will obtain:

pKa_1=-Log[6.9x10^-^3]=2.16

pKa_2=-Log[6.2x10^-^8]=7.20

pKa_3=-Log[4.8x10^-^13]=12.31

The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which  H_2PO_4^-^1 is the <u>acid</u> and HPO_4^-^2 is the <u>base</u>. Therefore the answer for the first question is B and the answer for the second question is C.

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26 Milkweed contains a poison known as cardenolides. Monarch butterflies eat the milkweed plant and hold on to this toxic compou
Amanda [17]

Cardenolides, with the chemical formula CH₁₈C₂₀H₁₅CHCO₂ have (D) 23 carbon atoms, 34 hydrogen atoms, and 2 oxygen atoms.

Milkweed contains a poison known as cardenolides. The chemical formula for cardenolides CH₁₈C₂₀H₁₅CHCO₂.

The subscripts in the formula represent the atomicities, that is the number of atoms of each element in each part of the formula.

We can calculate the total number of atoms of each element by adding its atomicities.

<h3>Carbon atoms</h3>

C =  1 + 20 + 1 + 1 = 23

<h3>Hydrogen atoms</h3>

H = 18 + 15 + 1 = 34

<h3>Oxygen atoms</h3>

O = 2

Cardenolides, with the chemical formula CH₁₈C₂₀H₁₅CHCO₂ have (D) 23 carbon atoms, 34 hydrogen atoms, and 2 oxygen atoms

Learn more: brainly.com/question/13348838

5 0
3 years ago
Given the chemical equation: 2 Pb + O2 → 2 PbO, if 51.8 grams of Pb are formed in this reaction, then 8.00 grams of O2 must have
Nutka1998 [239]

Answer:

If 51.8 of Pb is reacting, it will require 4.00 g of O2

If 51.8 g of PbO is formed, it will require 3.47 g of O2.

Explanation:

Equation of the reaction:

2 Pb + O2 → 2 PbO

From the equation of reaction, 2 moles of lead metal, Pb, reacts with 1 mole of oxygen gas, O2, to produce 2 moles of lead (ii) oxide, PbO

Molar mass of Pb = 207 g

Molar mass of O2 = 32 g

Molar mass of PbO = 207 + 32 = 239 g

Therefore 2 × 207 g of Pb reacts with 32 g of O2 to produce 2 × 239 g of PbO

= 414 g of Pb reacts with 32 g of O2 to produce 478 g of PbO

Therefore, formation of 51.8 g of PbO will require (32/478) × 51.8 of O2 = 3.47 g of O2.

If 51.8 of Pb is reacting, it will require (32/414) × 51.8 g of O2 = 4.00 g of O2

7 0
3 years ago
A 4Kg rock is rolling 10m/s find it’s kinetic energy
Lubov Fominskaja [6]
KE=.5mv^2
M=mass
v=velocity
.5(4)(100)=200
That should be the answer.
5 0
3 years ago
What type of bonding is found in the compound of2?
Ratling [72]

Answer:

chemical bond

Explanation:

because atom can join together by forming a chemical bond

7 0
3 years ago
What is atom economy?
bonufazy [111]

Answer:

The conversion efficiency of a chemical process.

Explanation:

Hope this helps!

5 0
3 years ago
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