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3 years ago

One acid, HA, has a pKa of 3.16 and another, HB, has a pKa of 4.14. Which is the stronger acid and why?

1 answer:

5 0

PKa is defined as the logarithm of the inverse of Ka, i.e

pKa = log ( 1 / Ka)

Ka is the dissociation constant of the acid. The larger Ka the stronger the acid.

On the other hand, from pKa = log (1 / Ka) the larger Ka the smaller 1 /Ka, and so the smaller log (1/Ka).

So, the relation between Ka and pKa is inverse, which means that an acid with greater value of pKa will have lower value Ka, and so it will be weaker or the smaller the pKa the stronger the acid.

Therefore, in our case HA has the lower pKa ant it will be the stronger acid.

Answer: HA is the stronger acid, because it has the lower pKa and pKa is inversely related to the strength of the acid.

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What is the percent composition of N H S O in (NH4)2SO4

Lena [83]

Answer:

The percent composition is 21% N, 6% H, 24% S and 49% O.

Explanation:

1st) The molar mass of (NH4)2SO4 is 132g/mol, and it represents the 100% of the mass composition.

In 1 mole of (NH4)2SO4, there are:

- 2 moles of N.

- 8 moles of H.

- 1 mole of S.

- 4 moles of O.

2nd) It is necessary to calculate the mass of each element, multiplying its molar mass by the number of moles:

- 2 moles of N (14g/mol) = 28g

- 8 moles of H (1g/mol) = 8g

- 1 mole of S (32g/mol) = 32g

- 4 moles of O (16g/mol) = 64g

3rd) With a mathematical rule of three we can calculate the percent composition of each element in the molecule of (NH4)2SO4:

$\begin{gathered} \text{ Nitrogen:} \\ 132g-100\% \\ 28g-x=\frac{28g*100\%}{132g} \\ x=21\% \end{gathered}$ $\begin{gathered} \text{ Hydrogen:} \\ 132g-100\operatorname{\%} \\ 8g-x=\frac{8g*100\operatorname{\%}}{132g} \\ x=6\% \end{gathered}$ $\begin{gathered} \text{ Sulfur:} \\ 132g-100\operatorname{\%} \\ 32g-x=\frac{32g*100\operatorname{\%}}{132g} \\ x=24\% \end{gathered}$ $\begin{gathered} \text{ Oxygen:} \\ 100\%-21\%-6\%-24\%=49\% \\ \\ \end{gathered}$

In this case, we can calculate the percent composition of Oxygen by subtracting the other percentages, since the total must be 100%.

So, the percent composition is 21% N, 6% H, 24% S and 49% O.

8 0

1 year ago

How much heat is required to melt 26.0 g of ice at its melting point?

MAXImum [283]

Answer:

Heat required to melt 26.0 g of ice at its melting point is 8.66 kJ.

Explanation:

Number of moles of water in 26 g of water: 26× $\frac{1}{18.02}$ moles

=1.44 moles

The enthalpy change for melting ice is called the entlaphy of fusion. Its value is 6.02 kj/mol.

we have relation as:

q = n × ΔH

where:

q = heat

n = moles

Δ H = enthalpy

So calculating we get,

q= 1.44*6.02 kJ

q= 8.66 kJ

We require 8.66 kJ of energy to melt 26g of ice.

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3 years ago

A que llamamos niveles y subniveles de energia?

Softa [21]

Answer:

agua

Explanation:

por que estamos en la planeta

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3 years ago

A cough sytup contains 0.5M dextromethophan. How many moles of the cough supressant are in 21.3mL of the cough syrup?

Doss [256]

Answer:

0.0107 mol

Explanation:

Multiply concentration by volume (in liters) to get moles.

0.5 M • 0.0213 L = 0.0107 mol

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3 years ago

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IrinaVladis [17]

I'd say it's suspension, but I'm not 100% sure...

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