The addition of hydrofluoric acid and __________ to water produces a buffer solution.

What is the pH of a 900 mL solution containing 3.40 grams of hydrocyanic acid

Allushta [10]

Answer:

$pH = 5.05$

Explanation:

pH is derived from the concentration of hydronium ions in a solution. Hydrocyanic acid is HCN.

First, we shall figure out the moles of HCN:

$\frac{3.4g}{27.03g/mol} = 0.125786$

If HCN was a strong acid:

HCN has a 1:1 ratio of H+ ions, the moles of H+ is also the same.

To find the molarity, we now divide by Liters. This gets us:

$\frac{0.125786 moles}{0.9L} = 0.139762 M$

Finally, we plug it into the definition of pH:

$pH = -log[H^{+} ]$

$pH = -log(0.139762)$

$pH = 0.855$

However, since HCN is a weak acid, it only partially dissociates. The $K_a$ of HCN is $6.2 * 10^{-10}$ .

$K_a = \frac{[H^+][A^-]}{[HA]}$

We can use an ice table to determine that when x = H+,

$K_a = \frac{x^2}{0.125786-x}$

$[H^+] = 8.83*10^{-6}$

$pH = -log[H^{+} ]$

$pH = -log(8.83 * 10^{-6} )$

$pH = 5.05$

7 0

4 years ago

Need help!! (10 Points) which liquid is the most viscous and why?

Hunter-Best [27]

Answer:

Honey

Explanation:

It’s honey because the item that was dropped in it is almost at the top and that means there is something sticky or force there holding it back!

4 0

3 years ago

PLEASE HELP ASAP!!!

kogti [31]

1 CH4 (g) + 2 O2 (g) -----> CO2 (g) + 2H2O(l) ΔH= - 890 kJ
1 mol 2 mol
1) If ΔH has minus, it means "release". We need only "release" choices.
2) From reaction
1 mol CH4 (g) "releases" ΔH= - 890 kJ - We do not have this choice.

2 mol O2 (g) "release" ΔH= - 890 kJ, so
1 mol O2 (g) "release" ΔH= - 445 kJ
Correct answer is B.

3 0

3 years ago

Read 2 more answers

The balanced equation for water is 2 H2 + O2 to 2 H2O. If I have 21.2g of a product , and I started with 5.6 g of H2, how many g

ANTONII [103]

Since 21.2 g H2O was produced, the amount of oxygen that reacted can be obtained using stoichiometry. The balanced equation was given: 2H₂ + O₂ → 2H₂O and the molar masses of the relevant species are also listed below. Thus, the following equation is used to determine the amount of oxygen consumed.

Molar mass of H2O = 18 g/mol

Molar mass of O2 = 32 g/mol

21.2 g H20 x 1 mol H2O/ 18 g H2O x 1 mol O2/ 2 mol H2O x 32 g O2/ 1 mol O2 = 18.8444 g O2

We then determine that 18.84 g of O2 reacted to form 21.2 g H2O based on stoichiometry. It is important to note that we do not need to consider the amount of H2 since we can derive the amount of O2 from the product. Additionally, the amount of H2 is in excess in the reaction.

7 0

4 years ago

If the [H+] in a solution is 1 × 10–1 mol/L, what is the [OH–]? Show your work.

AVprozaik [17]

Hello!

The basic equations to solve this is
pH = -log[H+]
pOH = -log[OH-]
pH + pOH = 14
------------------------------------------------------------------------------------------------------
Find pH

pH = -log(1 * 10^-1)
pH = 1
------------------------------------------------------------------------------------------------------
Find pOH
1 + pOH = 14

pOH = 13
------------------------------------------------------------------------------------------------------
Find OH-
[OH-] = 10^(-pOH)
[OH-] = 1 * 10^-13mo/L

The answer is $[OH-] = 1 * 10^{-13} mol/L$

Hope this helps!

3 0

4 years ago