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nydimaria [60]
2 years ago
12

If 50. 0 g of formic acid (HCHO2, ka = 1. 8 x 10^-4) and 30. 0 g of sodium formate (NaCHO2) are dissolved to make 500 ml. of sol

ution, the ph of this solution is? a. 4. 76 b. 3. 76 c. 3. 35 d. 4. 12
Chemistry
1 answer:
Ksju [112]2 years ago
7 0

If 50. 0 g of formic acid (HCHO2, ka = 1. 8 x 10^-4) and 30. 0 g of sodium formate (NaCHO2) are dissolved to make 500 ml. of solution, then the pH of this solution is 3.358.

Option C is correct option.

Given,

Given mass of formic acid = 50 g

Given mass of sodium formate = 30 g

Volume of formic acid = 500 ml

Volume of sodium formate = 500 ml

Molar mass of formic acid = 46 g

Molar mass of sodium formate = 68 g

<h3 /><h3>Calculation of concentration of formic acid and sodium formate</h3>

Molar concentration is defined as the ratio of number of moles and the volume of solution.

Concentration of formic acid

Ca = 50/(46×500)

      = 0.00217 m

Concentration of sodium formate

Cb = 30/(68×500)

     = 0.00088 m

Using Henderson Hesselbalch equation,

pH = pKa + log(Cb/Ca)

pKa = -log(1.8 × 10^(-4))

      = 3.75

Substituting the value of pKa we get,

pH = 3.75 + log(0.00088/0.00217)

pH = 3.75-0.392

pH = 3.35

Thus the value of pH of solution containing formic acid and sodium formate is 3.35.

learn more about pH :

brainly.com/question/13423434

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ikadub [295]

Answer:

74mL

Explanation:

Given parameters:

Molar mass of citric acid = 192g/mol

Molar mass of baking soda = 84g/mol

Concentration of citric acid  = 0.8M

Mass of baking powder = 15g

Unknown parameters:

Volume of citric acid = ?

Solution

       Equation of the reaction:

            C₆H₈O₇ + 3NaHCO₃ → Na₃C₆H₅O₇ + 3H₂O + 3CO₂

Procedure:

  • We work from the known parameters to the unknown. From the statement of the problem, we can approach the solution from the parameters of the baking powder.
  • From the baking powder, we can establish a molar relationship between the two reactants. We employ the mole concept in this regard.
  • We find the number of moles of the baking powder that went into the reaction using the expression below:

                Number of moles = \frac{mass}{molar mass}

                Number of moles =  \frac{15}{84} = 0.179mole

  • From the equation of the reaction, we can find the number of moles of the citric acid:

             3 moles of baking powder reacted with 1 mole of citric acid

 0.179 moles of baking powder would react with \frac{0.179}{3}:

          This yields 0.059mole of citric acid

  • To find the volume of the citric acid, we use the mole expression below:

    Volume of citric acid = \frac{number of moles}{concentration}

Volume of citric acid = \frac{0.059}{0.8} = 0.074L

Expressing in mL gives 74mL

               

4 0
3 years ago
What is the crystalline arrangement of atoms shown here?
mixer [17]

Answer: Answer:

"The arrangement of atoms or ions in a crystal " is described by the terms body-centered cubic and face-centered cubic.

Explanation:

Face centred cubic system explains the crystal structure where an atom is present at each cubic corner of the crystal  and the centre of each cube face. Meaningfully, a closed packed plane where at each "face of the cube" atoms touch the alongside face diagonals.

Whereas in body centric cube system has the lattice point present at the 8 corners of  cell and an additional one at the center of the cell. Thus, both explains how the atom or ions are  placed or arranged in a crystal.

Explanation: Hope this helps :)

4 0
3 years ago
How do scientists distinguish between an element and a compound? List two elements and two compounds.
Vsevolod [243]
The difference between an element and a compound is that an element is composed of only one kind of atom while a compound is composed of at least 2 kinds of atoms. The properties of an element and the compound the atoms has to form are different physically and chemically.Example of element are O and H, while compound examples are H2O and H2O2. 
7 0
3 years ago
Determine the pH of a 2.8 ×10−4 M solution<br> of Ca(OH)2.
shepuryov [24]

Answer:

pH = 10.75

Explanation:

To solve this problem, we must find the molarity of [OH⁻]. With the molarity we can find the pOH = -log[OH⁻]

Using the equation:

pH = 14 - pOH

We can find the pH of the solution.

The molarity of Ca(OH)₂ is 2.8x10⁻⁴M, as there are 2 moles of OH⁻ in 1 mole of Ca(OH)₂, the molarity of [OH⁻] is 2*2.8x10⁻⁴M = 5.6x10⁻⁴M

pOH is

pOH = -log 5.6x10⁻⁴M

pOH = 3.25

pH = 14-pOH

<h3>pH = 10.75</h3>
3 0
3 years ago
What volume of o2 is needed to react fully with 720. Ml of nh3
Galina-37 [17]

Ammonia undergoes combustion with oxygen to produce nitric oxide and water. The volume of the oxygen required to react with 720 ml of ammonia is 900 ml.

<h3>What is volume?</h3>

Volume is the area occupied by the substance and is the ratio of the mass to the density.

At STP, 1 mole of gas occupies 22.4 L of volume

Given,

Volume of ammonia reacted = 0.720 L

The combustion reaction is shown as,

\rm 4NH_{3} + 5O_{2} \rightarrow 4NO +6H_{2}O

From the stoichiometry of the reaction, it can be said that,

(4 \times  22.4) L of ammonia reacts with (5 \times  22.4) L of oxygen gas.

So, 0.720 L of  ammonia will react with:

\dfrac{ (5 \times  22.4)}{(4 \times  22.4)} \times 0.720 = 0.9 \;\rm L

Therefore, the volume of oxygen required is 900 mL.

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6 0
2 years ago
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