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2 years ago

A 25.0 mL sample of HCI reacted with 20.0 mL of 2.00 M NaOH. What is the molarity of the HCI?

Chemistry

1 answer:

Lemur [1.5K]2 years ago

5 0

Answer:

Molarity of HCl = 1.6M

Explanation:

The chemical reaction equation is;

HCl(aq) + NaOH(aq) —> NaCl(aq) + H2O(l)

Now, molarity = number of moles/volume

Thus, for NaOH, we have;

Number of moles = molarity × volume = 2M × (20/1000) L

Number of moles = 0.04 moles

Using the coefficients in the chemical equation above, we can find the corresponding number of moles for HCl.

Number of moles of HCl = 0.04 moles NaOH × (1 mole of HCl/1 mole of HCl) = 0.04 moles of HCl

Thus;

Molarity of HCl = 0.04/(25/1000)

Molarity of HCl = 1.6M

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What is the pH of this solution?

Vesnalui [34]

Answer:

pH = 11.216.

Explanation:

Hello there!

In this case, according to the ionization of ammonia in aqueous solution:

$NH_3+H_2O\rightleftharpoons NH_4^++OH^-$

We can set up its equilibrium expression in terms of x as the reaction extent equal to the concentration of each product at equilibrium:

$Kb=\frac{[NH_4^+][OH^-]}{[NH_3]} \\\\1.80x10^{-5}=\frac{x*x}{0.150-x}$

However, since Kb<<<1 we can neglect the x on bottom and easily compute it via:

$1.80x10^{-5}=\frac{x*x}{0.150}\\\\x=\sqrt{1.80x10^{-5}*0.150}=1.643x10^{-3}M$

Which is also:

$[OH^-]=1.643x10^{-3}M$

Thereafter we can compute the pOH first:

$pOH=-log(1.643x10^{-3}M)\\\\pOH=2.784$

Finally, the pH turns out:

$pH=14-2.784\\\\pH=11.216$

Regards!

5 0

3 years ago

if the percent by volume is 2% and the volume of solution is 250 mL what is the volume of solute and solution

Liula [17]

Answer:

Solute = 5 mL; solution = 250 mL

Explanation:

The formula for percent by volume is

$\text{Percent by volume} = \dfrac{\text{Volume of solute}}{\text{Volume of solution}}\times 100 \, \%$

If you have 250 mL of a solution that is 2 % v/v,

$\begin{array}{rcl}2 \, \% & = & \dfrac{\text{Volume of solute}}{\text{250 mL}}\times 100 \, \%\\\\2 \times \text{ 250 mL} & = & \text{Volume of solute} \times 100\\\text{Volume of solute} & = & \dfrac{2 \times 250\text{ mL}}{100}\\\\ & = & \textbf{5 mL}\\\end{array}$

If there is no change of volume on mixing,

Volume of solution = 250 mL

-Volume of solute = 5

Volume of solvent = 245 mL

5 0

3 years ago

Control activities are performed within processes (e.g., segregation of duties required in processing cash receipt transactions)

galina1969 [7]

Answer:

a. True

Explanation:

The control objectives seek to support the fulfillment of the critical factors of business success, in order to finally support the achievement of the institutional objectives, on this the CITI is based

It is very important to clearly identify the relationships of the control objectives with other internal control elements such as:

· Critical success factors receive direct support from control objectives to support compliance.

· The control objectives are made up of control goals, which allow them to have a more detailed perspective of the control objectives and at the same time facilitate the evaluation of their compliance.

CITI CONCEPT:

It is the set of administration elements that a company establishes in a coordinated way so that the use of information technology resources effectively supports the institutional objectives of the company

6 0

3 years ago

The effectiveness of a chemical sanitizer can be limited by

Serjik [45]

Chemical sanitizer effectiveness, decreases with increase in pH . And most soap and detergent are alkaline in nature, that limits its effectiveness. So they should be rinsed off completely for proper effectiveness of santizer. So improper rinsing limits the effectiveness of a sanitizer.

So , the answer is improper rinsing after that still a detergent residue remains limits the effectiveness of sanitizer.

7 0

3 years ago

Which of the following is not an example of a polymer? (2 points)

ahrayia [7]

Answer is "sucrose".

Polymer is a large molecule which is made from repeating units. The smallest repeating unit is called as monomer. Polystyrene, nylon and PVC are examples for polymers. But sucrose is a disaccharide which is made from glucose and fructose. Hence, sucrose is not an example of polymer.

3 0

3 years ago