A gas occupies a volume of 0.20 L at 25 kPa. What volume will the gas occupy at 2.0 kPa?

A chemist must prepare of 800.0 ml potassium hydroxide solution with a pH of 13.00 at 25Â°.

ArbitrLikvidat [17]

Answer:

4.48 grams is the mass of potassium hydroxide that the chemist must weigh out in the second step.

Explanation:

The pH of the solution = 13.00

pH + pOH = 14

pOH = 14 - pH = 14 - 13.00 = 1.00

$pOH=-\log[OH^-]$

$1.00=-\log[OH^-]$

$[OH^-]=10^{-1.00} M=0.100 M$

$KOH(aq)\rightarrow K^+(aq)+OH^-(aq)$

$[KOH]=[OH^-]=[K^+]=0.100 M$

Molariy of the KOH = 0.100 M

Volume of the KOH solution = 800 mL= 0.800 L

1 mL = 0.001 L

Moles of KOH = n

$Molarity=\frac{Moles}{Volume(L)}$

$0.100 M=\frac{n}{0.800 L}$

n = 0.0800 mol

Mass of 0.0800 moles of KOH :

0.0800 mol × 56 g/mol = 4.48 g

4.48 grams is the mass of potassium hydroxide that the chemist must weigh out in the second step.

4 0

3 years ago

Please help i will give brainliest!!! thank you =)

Anastasy [175]

Answer:

Answer choice B. 2

Explanation:

7 0

2 years ago

how to determine the net charge of the tripeptide Asp-Gly-Leu at pH 7. Can someone show in details and tricks on how to solve it

Ugo [173]

Answer:

0!

Explanation:

You need to search your pKa values for Asn (2.14, 8.75), Gly (2.35, 9.78) and Leu(2.33, 9.74), the first value corresponding to -COOH, the second to -NH3 (a third value would correspond to an R group, but in this case that does not apply), and we'll build a table to find the charges for your possible dissociated groups at indicated pH (7), we need to remember that having a pKa lower than the pH will give us a negative charge, having a pKa bigger than pH will give us a positive charge:

-COOH -NH3

pH 7------------------------------------------------------

Asn - +

Gly - +

Leu - +

Now that we have our table we'll sketch our peptide's structure:

This will allow us to see what groups will be free to react to the pH's value, and which groups are not reacting to pH because are forming the bond between amino acids. In this particular example only -NH group in Ans and -COOH in Leu are exposed to pH, we'll look for these charges in the table and add them to find the net charge:

+1 (HN-Asn)

-1 (Leu-COOH)

=0

The net charge is 0!

I hope you find this information useful and interesting! Good luck!

5 0

3 years ago

Which element would make a poor, brittle conductor? use the periodic table for help. a. sulfur b. boron c. cobalt d. calcium?

Greeley [361]

I think the answer is C or B

8 0

3 years ago

What is the molarity of a 3.0 solution of magnesium chloride prepared with 9.0 molecules of MgCl2 A. 6.0 M B. 3.0 M C. 27.0 M D.

Gala2k [10]

Answer:

Option B. 3.0 M

Explanation:

From the question given above, the following data were obtained:

Volume of solution = 3.0 L

Mole of MgCl₂ = 9 moles

Molarity =?

Molarity can simply be defined as the mole of solute per unit litre of the solution. Mathematically, it can be expressed as:

Molarity = mole of solute /Volume of solution

With the above formula, we can obtain the molarity of the solution as follow:

Volume of solution = 3.0 L

Mole of MgCl₂ = 9 moles

Molarity =?

Molarity = mole of solute /Volume of solution

Molarity = 9 / 3

Molarity = 3 mol/L = 3.0 M

Thus, the molarity of the solution is 3 M

8 0

3 years ago