4. Since water possess a partially positive and a negative end, we refer to it as?

Your job is to determine the concentration of ammonia in a commercial window cleaner. In the titration of a 25.0 mL sample of th

ruslelena [56]

Answer:

The initial concentration of ammonia is 0.14 M and the pH of the solution at equivalence point is 5.20

<u>Explanation:</u>

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$ .....(1)

Molarity of HCl solution = 0.164 M

Volume of solution = 23.8 mL = 0.0238 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$0.164M=\frac{\text{Moles of HCl}}{0.0238L}\\\\\text{Moles of HCl}=(0.146mol/L\times 0.0238L)=0.0035mol$

The chemical equation for the reaction of ammonia and HCl follows:

$NH_3+HCl\rightarrow NH_4^++Cl^-$

By Stoichiometry of the reaction:

1 mole of HCl reacts with 1 mole of ammonia

So, 0.0035 moles of HCl will react with = $\frac{1}{1}\times 0.0035=0.0035mol$ of ammonia

Calculating the initial concentration of ammonia by using equation 1:

Moles of ammonia = 0.0035 moles

Volume of solution = 25 mL = 0.025 L

Putting values in equation 1, we get:

$\text{Initial concentration of ammonia}=\frac{0.0035mol}{0.025L}=0.14M$

By Stoichiometry of the reaction:

1 mole of ammonia produces 1 mole of ammonium ion

So, 0.0035 moles of ammonia will react with = $\frac{1}{1}\times 0.0035=0.0035mol$ of ammonium ion

Calculating the concentration of ammonium ion by using equation 1:

Moles of ammonium ion = 0.0035 moles

Volume of solution = [23.8 + 25] mL = 48.8 mL = 0.0488 L

Putting values in equation 1, we get:

$\text{Molarity of ammonium ion}=\frac{0.0035mol}{0.0488L}=0.072M$

To calculate the acid dissociation constant for the given base dissociation constant, we use the equation:

$K_w=K_b\times K_a$

where,

$K_w$ = Ionic product of water = $10^{-14}$

$K_a$ = Acid dissociation constant

$K_b$ = Base dissociation constant = $1.8\times 10^{-5}$

$10^{-14}=1.8\times 10^{-5}\times K_a\\\\K_a=\frac{10^{-14}}{1.8\times 10^{-5}}=5.55\times 10^{-10}$

The chemical equation for the dissociation of ammonium ion follows:

$NH_4^+\rightarrow NH_3+H^+$

The expression of $K_a$ for above equation follows:

$K_a=\frac{[NH_3][H^+]}{[NH_4^+]}$

We know that:

$[NH_3]=[H^+]=x$

$[NH_4^+]=0.072M$

Putting values in above expression, we get:

$5.55\times 10^{-10}=\frac{x\times x}{0.072}\\\\x=6.32\times 10^{-6}M$

To calculate the pH concentration, we use the equation:

$pH=-\log[H^+]$

We are given:

$[H^+]=6.32\times 10^{--6}M$

$pH=-\log (6.32\times 10^{-6})\\\\pH=5.20$

Hence, the initial concentration of ammonia is 0.14 M and the pH of the solution at equivalence point is 5.20

5 0

3 years ago

¿Quién estableció el concepto moderno de elemento?

Zina [86]

Answer:

Robert Boyle

Explanation:

En muchos textos se suele considerar a Robert Boyle como el científico que introdujo en la Química un concepto de elemento diferente al empleado por los aristotélicos o por los alquimistas y que sirvió de antecedente al que formulara Lavoisier en 1789.

7 0

2 years ago

HELP MEEEE ASAP PLEASEEEE !!!!!!!!

jasenka [17]

Ok, I will help you answer but it is very hard to read could you enlarge it first?

Thanks!

5 0

3 years ago

You set up an experiment to determine the conditions needed to form the gemstones with the most clarity. You gather data from 5

Andreyy89

I’m in chemistry too. Giving this my best guess I’d say
Independent: Gem Mines
Dependent: Gem clarity
Controlled: Temperature

6 0

3 years ago

Read 2 more answers

Traveling at the speed of light - how long would it take, in years, to reach the top of the pile of balls? Show all calculations

marusya05 [52]

The time taken for the object to reach to top of pile is 0.012 year.

<h3>Time of motion </h3>

The time taken for the object to reach to top of pile is calculated as follows;

time of motion = distance traveled/speed

time of motion = (1.1 x 10¹⁴ x 10³ m)/(3 x 10⁸ m/s)

where;

speed of light = 3 x 10⁸ m/s

time of motion = 3.67 x 10⁵ sec = 0.012 year

Thus, the time taken for the object to reach to top of pile is 0.012 year.

Learn more about time of motion here: brainly.com/question/2364404

#SPJ1

7 0

2 years ago