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2 years ago

A 52.0 mL volume of 0.25 M HBr is titrated with 0.50 M KOH. Calculate the pH after addition of 26.0 mL of KOH at 25 ∘C.

1 answer:

7 0

The balanced equation for the above reaction is
HBr + KOH ---> KBr + H₂O
stoichiometry of HBr to KOH is 1:1
HBr is a strong acid and KOH is a strong base and they both completely dissociate.
The number of HBr moles present - 0.25 M / 1000 mL/L x 52.0 mL = 0.013 mol
The number of KOH moles added - 0.50 M / 1000 mL/L x 26.0 mL = 0.013 mol
the number of H⁺ ions = number of OH⁻ ions
therefore complete neutralisation occurs.
Therefore solution is neutral. At 25 °C, when the solution is neutral, pH = 7.
Then pH of solution is 7

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If 4.00 g of gallium is reacted with 5.50 g of arsenic how many grams of the excess reactant are left at the end of the reaction

vivado [14]

<h2>The grams of the excess reactant that are left at the end of reaction is</h2><h2>= 1.2014 grams</h2>
<h3>calculation</h3>

find the moles of each reactant

moles = mass/molar mass

molar mass of Ga= 69.7 g/mol

molar mass of As= 74.9 g/mol

mole of Ga = 4 g÷69.7 g/mol=0.05739 moles

moles of As=5.50 g÷74.9 g/mol =0.07343 moles

0.05739 moles of Ga reacted completely with 0.05739 moles of As therefore As was in excess

Therefore the moles of As that did not react = 0.07343 - 0.05739=0.01604 moles

mass that did not react = moles that was left x molar mass of As

that is; 0.01604 x 74.9=1.2014 grams

8 0

2 years ago

Read 2 more answers

A 1.555-g sample of baking soda decomposes with heat to produce 0.991 g Na2CO3. Refer to Example Exercise 14.l and show the calc

Sunny_sXe [5.5K]

Answer:

a) 101%

b)59.7%

Explanation:

The equation for the thermal decomposition of baking soda is shown;

2NaHCO3 → Na2CO3 + H2O + CO2

Number of moles of baking soda= mass/molar mass= 1.555g/84.007 g/mol = 0.0185 moles

From the reaction equation;

2 moles of baking soda yields 1 mole of sodium carbonate

0.0185 moles of baking soda will yield = 0.0185 moles ×1 /2 = 9.25 ×10^-3 moles of sodium carbonate.

Therefore, mass of sodium carbonate= 9.25 ×10^-3 moles × 106gmol-1= 0.9805 g of sodium carbonate. This is the theoretical yield of sodium carbonate.

%yield = actual yield/theoretical yield ×100

% yield = 0.991/0.9805 ×100

%yield = 101%

Since ;

2NaHCO3 → Na2CO3 + H2O + CO2

And H2O + CO2 ---> H2CO3

Hence I can write, 2NaHCO3 → Na2CO3 + H2CO3

Molar mass of H2CO3= 62.03 gmol-1

Molar mass of baking soda= 84 gmol-1

Therefore, mass of baking soda=

0.325/62.03 × 2 × 84 = 0.88 g of NaHCO3

% of NaHCO3= 0.88/1.473 × 100 = 59.7%

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2 years ago

Arrange these compounds by their expected vapor pressure: H2O NCl3 Br2

Tamiku [17]

Answer: Given compounds are arranged in decreasing order of their vapor pressure as follows.

$Br_{2}$ > $NCl_{3}$ > $H_{2}O$

Explanation:

Vapor pressure is defined as the pressure exerted by the vapors which are present on the surface of a liquid. Less is the intermoecular forces present within the molecules of a substance more will be its vapor pressure.

For example, $Br_{2}$ is a gas and there exists Vander waal forces between its molecules. Hence, it has more vapor pressure than $NCl_{3}$ and $H_{2}O$ .

In $H_{2}O$ , there exists hydrogen bonding which is stronger than bonding present in $NCl_{3}$ . So, $H_{2}O$ has low vapor pressure.

In $NCl_{3}$ , there exists dipole-dipole interaction which is stronger than Vander waal forces but weaker than hydrogen bonding.

Therefore, given compounds are arranged in decreasing order of their vapor pressure as follows.

$Br_{2}$ > $NCl_{3}$ > $H_{2}O$

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2 years ago

A few drops of a mixture of sodium hydroxide(NaOH) solution and copper (II) tetraoxosulphate (VI) solution were added to a sampl

Kaylis [27]

Answer:

It is a test for proteins in urine

Explanation:

The Biuret reagent is made of sodium hydroxide (NaOH) and hydrated copper(II) sulfate. The biuret reagent is commonly used to test for proteins. The biuret test is also known as Piotrowski's test. It is a chemical test commonly used in detecting the presence of peptide bonds. In the presence of peptides, a copper(II) ion forms purple-colored coordination complexes in an alkaline solution.

Hence the addition of this Biuret reagent to a urine sample in a test tube aims to detect the presence or absence of proteins in the given urine sample. If there is protein in the urine sample, the blue colour of the Biuret reagent turns purple. If there is no protein in the urine sample, the Biuret reagent remains blue.

In an alkaline solution, copper II is able to form a complex with the peptide bonds in proteins. Once this complex has been formed, the Biuret solution turns from a blue color to a purple color. This is the positive test for proteins.

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2 years ago

What alkene reacts the fastest with HBr?

Rasek [7]

The first step in the reaction is the double bond of the Alkene going after the H of HBr. This protonates the Alkene via Markovnikov's rule, and forms a carbocation. The stability of this carbocation dictates the rate of the reaction.

<span>So to solve your problem, protonate all your Alkenes following Markovnikov's rule, and then compare the relative stability of your resulting carbocations. Tertiary is more stable than secondary, so an Alkene that produces a tertiary carbocation reacts faster than an Alkene that produces a secondary carbocation.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!
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2 years ago

Read 2 more answers