Diferencias entre Neoclásico. Marxista y Estructuralista.

A chemistry graduate student is given 125.mL of a 1.00M benzoic acid HC6H5CO2 solution. Benzoic acid is a weak acid with =Ka×6.3

lubasha [3.4K]

Answer:

53.9 g

Explanation:

When talking about buffers is very common the problem involves the use of the Henderson Hasselbach formula:

pH = pKa + log [A⁻]/[HA]

where [A⁻] is the concentration of the conjugate base of the weak acid HA, and [HA] is the concentration of the weak acid.

We can calculate pKₐ from the given kₐ ( pKₐ = - log Kₐ ), and from there obtain the ratio [A⁻]/HA].

Since we know the concentration of HC6H5CO2 and the volume of solution, the moles and mass of KC6H5CO2 can be determined.

So,

4.63 = - log ( 6.3 x 10⁻⁵ ) + log [A⁻]/[HA] = - (-4.20 ) + log [A⁻]/[HA]

⇒ log [A⁻]/[HA] = 4.63 - 4.20 = log [A⁻]/[HA]

0.43 = log [A⁻]/[HA]

taking antilogs to both sides of this equation:

10^0.43 = [A⁻]/[HA] = 2.69

[A⁻]/ 1.00 M = 2.69 ⇒ [A⁻] = 2.69 M

Molarity is moles per liter of solution, so we can calculate how many moles of C6H5CO2⁻ the student needs to dissolve in 125. mL ( 0.125 L ) of a 2.69 M solution:

( 2.69 mol C6H5CO2⁻ / 1L ) x 0.125 L = 0.34 mol C6H5CO2⁻

The mass will be obtained by multiplying 0.34 mol times molecular weight for KC6H5CO2 ( 160.21 g/mol ):

0.34 mol x 160.21 g/mol = 53.9 g

3 0

3 years ago

555mL of gas is combined at standard temperature and pressure(STP). The volume changes to 660.mL at 30.5 °C. What is the new pre

liberstina [14]

Answer:0.94

Explanation:

4 0

2 years ago

Which is the limiting reactant if we start with 30.0 g Al and 30.0 h O2

lorasvet [3.4K]

Al

Explanation:

The limiting reactant will be Al:

4Al + 3O₂ → 2Al₂O₃

The limiting reactant is the reactant in short supply in a chemical reaction.

Given parameters:

Mass of Al = 30g Molar mass = 27g/mol

Number of moles = $\frac{mass}{molar mass}$ = $\frac{30}{27}$

Number of moles of Al = 1.111 mole

Mass of O₂ = 30g, molar mass = 32g/mol

Number of moles = $\frac{30}{32}$ = 0.94mol

In the reaction:

4 moles of Al reacted with 3 moles of O₂

1.11moles of Al will require $\frac{1.11 x3}{4}$ = 0.83mole to react

But we have been given 0.94mole of O₂. This is more than required.

Therefore O₂ is in excess and Al is the limiting reactant.

Learn more:

Limiting reagents brainly.com/question/6078553

#learnwithBrainly

4 0

2 years ago

A buret is filled with 0.1517 M naoh A 25.0 mL portion of an unknown acid and two drops of indicator are added to an Erlenmeyer

antiseptic1488 [7]

Answer:

molarity of acid =0.0132 M

Explanation:

We are considering that the unknown acid is monoprotic. Let the acid is HA.

The reaction between NaOH and acid will be:

$NaOH+HA--->NaA+H_{2}O$

Thus one mole of acid will react with one mole of base.

The moles of base reacted = molarity of NaOH X volume of NaOH

The volume of NaOH used = Final burette reading - Initial reading

Volume of NaOH used = 22.50-0.55= 21.95 mL

Moles of NaOH = 0.1517X21.95=3.33 mmole

The moles of acid reacted = 3.33 mmole

The molarity of acid will be = $\frac{mmole}{volumne(mL)}=\frac{0.33}{25}=0.0132M$

4 0

3 years ago

Which actions represent endothermic reactions? Check all that apply.

marishachu [46]

Answer:

Well, one is if heat is absorbed by the system from the surroundings, the system gains heat from the surroundings and so the temperature of the surroundings decreases.

Explanation:

8 0

3 years ago

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