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3 years ago

How to calculate percentage change in mass

1 answer:

3 0

In order to find the percentage change in mass, you must divide Change in Mass by Initial Mass. After that, you divide the change in mass by the initial mass of your substance.

This calculation shows what proportion of the initial mass changed. To find the percent change, simply multiply this number by 100

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Your task is to create a buffered solution. You are provided with 0.10 M solutions of formic acid and sodium formate. Formic aci

Anton [14]

Answer:

15.2mL of the 0.10M sodium formate solution and 4.8mL of the 0.10M formic acid solution.

Explanation:

To find the pH of a buffer based on the concentration of the acid and conjugate base we must use Henderson-Hasselbalch equation:

pH = pKa + log [A⁻] / [HA]

Where [A⁻] could be taken as moles of the sodium formate and [HA] moles of the formic acid

4.25 = 3.75 + log [A⁻] / [HA]

0.5 = log [A⁻] / [HA]

3.162 = [A⁻] / [HA] (1)

As both solutions are 0.10M and you want to create 20mL of the buffer, the moles are:

0.10M * 20x10⁻³L =

2x10⁻³moles = [A⁻] + [HA] (2)

Replacing (2) in (1):

3.162 = 2x10⁻³moles - [HA] / [HA]

3.162 [HA] = 2x10⁻³moles - [HA]

4.162[HA] = 2x10⁻³moles

[HA] = 4.805x10⁻⁴ moles

[A⁻] = 2x10⁻³moles - 4.805x10⁻⁴ moles = 1.5195x10⁻³moles

That means, to create the buffer you must add:

[A⁻] = 1.5195x10⁻³moles * (1L / 0.10mol) = 0.0152L =

<h3>15.2mL of the 0.10M sodium formate solution</h3>

[HA] = 4.805x10⁻⁴ moles * (1L / 0.10mol) = 0.0048L =

<h3>4.8mL of the 0.10M formic acid solution</h3>

4 0

3 years ago

When sodium and oxygen react to form an ionic compound, the mass of the compound ____ the sum of the masses of the individual el

Anna007 [38]

Hi Lara

The answer is : C

Is equal to

I hope that's help!

5 0

3 years ago

Read 2 more answers

Acetaldehyde decomposes at 750 K: CH3CHO → CO + CH4. The reaction is first order in acetaldehyde and the half-life of the reacti

Degger [83]

Answer:

k = 1.3 x 10⁻³ s⁻¹

Explanation:

For a first order reaction the integrated rate law is

Ln [A]t/[A]₀ = - kt

where [A] are the concentrations of acetaldehyde in this case, t is the time and k is the rate constant.

We are given the half life for the concentration of acetaldehyde to fall to one half its original value, thus

Ln [A]t/[A]₀ = Ln 1/2[A]₀/[A]₀= Ln 1/2 = - kt

- 0.693 = - k(530s) ⇒ k = 1.3 x 10⁻³ s⁻¹

4 0

3 years ago

Why dilute H2SO4 is added to oxali acid solution in redox reaction

Sphinxa [80]

To prevent the hydrolysis and to catalyse the reaction.

Explanation:

Sulphuric acid is the catalyst and also a dehydrating agent in this reaction.

Sulphuric acid is using in redox reaction because sulphuric acid is providing H+ ions which is necessary for this reaction to occur more quickly, but the sulphate ions from the sulphuric acid barely react during this process. So H2SO4 is adding in this reaction to make it more acidic.

H2SO4 is preventing hydrolysis by providing excess H+ ions into the reaction. H2SO4 is stable towards the direction of oxidation.

7 0

3 years ago

Calculate the percent ionization of nitrous acid in a solution that is 0.139 M in nitrous acid. The acid dissociation constant o

anzhelika [568]

Ok first, we have to create a balanced equation for the dissolution of nitrous acid.

HNO2 <-> H(+) + NO2(-)

Next, create an ICE table

HNO2 <--> H+ NO2-
[]i 0.139M 0M 0M
Δ[] -x +x +x
[]f 0.139-x x x

Then, using the concentration equation, you get

4.5x10^-4 = [H+][NO2-]/[HNO2]

4.5x10^-4 = x*x / .139 - x

However, because the Ka value for nitrous acid is lower than 10^-3, we can assume the amount it dissociates is negligable,

assume 0.139-x ≈ 0.139

4.5x10^-4 = x^2/0.139

Then, we solve for x by first multiplying both sides by 0.139 and then taking the square root of both sides.

We get the final concentrations of [H+] and [NO2-] to be x, which equals 0.007M.

Then to find percent dissociation, you do final concentration/initial concentration.

0.007M/0.139M = .0503 or

≈5.03% dissociation.

4 0

3 years ago

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