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ale4655 [162]
2 years ago
7

10 pointss..******^^

Chemistry
2 answers:
Kisachek [45]2 years ago
7 0

Answer:

close off completely

Explanation:

get wider

koban [17]2 years ago
3 0

Answer:

UwU

Explanation:

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Imagine you need to explain to a friend how to convert a value on a food label to one that is measured in grams. Assume the pack
Mariulka [41]

Answer:

453.592 grams

Explanation:

Given

Mass = 1 lb

Required.

Convert to grams using dimensional analysis

Represent 1 lb with x g

In unit conversion, we have that.

1 lb = 453.592 g

So:

Getting the equivalent of lb in g, we have:

x g = 1 lb * (453.592 g/ 1 lb)

x g = 1 * 453.592 g

x g = 453.592 grams

Hence:

The equivalent of 1 lb in grams is 453.592 grams

4 0
3 years ago
To understand the relation between the strength of an acid or a base and its pKa and pKb values. The degree to which a weak acid
elena-14-01-66 [18.8K]

Answer:

pKa = 3.675

Explanation:

  • pKa = - Log Ka

∴ <em>C</em> X-281 = 0.079 M

∴ pH = 2.40

let X-281 a weak acid ( HA ):

∴ HA ↔ H+ + A-

⇒ Ka = [H+] * [A-] / [HA]

mass balance:

⇒<em> C</em> HA = 0.079 M = [HA] + [A-]

⇒ [HA] = 0.079 - [A-]

charge balance:

⇒ [H+] = [A-] + [OH-]... [OH-] is negligible; it comes from to water

⇒ [H+] = [A-]

∴ pH = - log [H+] = 2.40

⇒ [H+] = 3.981 E-3 M

replacing in Ka:

⇒ Ka = [H+]² / ( 0.079 - [H+] )

⇒ Ka = ( 3.981 E-3 )² / ( 0.079 - 3.981 E-3 )

⇒ Ka = 2.113 E-4

⇒ pKa = - Log ( 2.113 E-4 )

⇒ pKa = 3.675

8 0
3 years ago
Which actions represent endothermic reactions? Check all that apply.
marishachu [46]

Answer:

Well, one is if heat is absorbed by the system from the surroundings, the system gains heat from the surroundings and so the temperature of the surroundings decreases.

Explanation:

8 0
3 years ago
Read 2 more answers
A student made an initial 1:5 dilution of protein lysate. Then 2mL of that was added to 8mL of water. Lastly, the student made a
Licemer1 [7]

Answer:

The final dilution is 1:400

Explanation:

Let's analyze what we are told: we have an initial 1:5 dilution of protein lysate. This means that the initial solution (stock solution) was diluted 5 times. Then, from this dilution the student prepared another dilution taking 2 mL of the first dilution in 8 mL of water. This is the same as saying we took 1 mL of first dilution in 4 mL of water (the ratio is the same), so we now have a second 1:4 dilution of the first dilution (1:5). Finally, the student made a third 1:20 dilution, this means that the second dilution was further diluted 20 times.

So, to calculate the final dilution of protein lysate, we have to multiply all the dilution factors of every dilution prepared: in this case we have a final dilution of 1:20, this means we have a factor dilution of 20. But it was previously diluted 4 times, so we have a factor dilution of 20×4 = 80. However, this dilution was also previously diluted 5 times, so the new dilution factor is 80 × 5 = 400

This means that the final dilution of the compound was diluted a total of 400 times compared to the initial concentration of stock solution.

3 0
3 years ago
In a chemical equation, the symbol that means "dissolved in water" is _____. (s) (l) (aq) (g)
Paraphin [41]
In a chemical equation, the symbol that means “dissolved in water” is (aq).
8 0
2 years ago
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