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Sophie [7]
3 years ago
5

Aspirin (acetylsalicylic acid, C9H8O4) is a weak monoprotic acid. To determine its acid-dissociation constant, a student dissolv

ed 2.00 g of aspirin in 0.600 L of water and measured the pH. What was the Ka value calculated by the student if the pH of the solution was 2.61?
Chemistry
1 answer:
BabaBlast [244]3 years ago
8 0

Answer:

The Ka is 3.74 *10^-4

Explanation:

Step 1: Data given

Mass of aspirin = 2.00 grams

Volume of water = 0.600 L

pH of solution = 2.61

Molar mass of acetylsalicylic acid = 180 g/mol

Step 2: The balanced equation

C9H8O4 + H2O ⇆ H3O+ + C9H7O4-

Step 3: Calculate moles acetylsalicylic acid

Moles acetylsalicylic acid = mass / molar mass

Moles acetylsalicylic acid = 2.00 grams / 180 g/mol

Moles acetylsalicylic acid = 0.0111 moles

Step 4: The initial concentration

[C9H8O4] = 0.0111 moles / 0.600 L = 0.0185 M

[H3O+] = 0M

[C9H8O4-] = 0M

Step 5: The concentration at the equilibrium

[C9H8O4] =0.0185 - X M

[H3O+] = XM

[C9H8O4-] = XM

Step 6: Calculate Ka

Ka = [H3O+][C9H7O4-] / [C9H8O4]

Ka = x² / (0.0185 - x)

pH = 2.61;  [H3O+] = 10^-pH = 10^-2.61 = 0.00245 = x

Ka = (0.00245)² / (0.0185 - 0.00245) = 3.74 * 10^-4

The Ka is 3.74 *10^-4

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Answer:

Torrey's neighbour is incorrect because increase in kinetic energy is proportional to velocity.  If the velocity increases so will the object's kinetic energy.  Because the mass is constant, if the velocity increases, so does the kinetic energy.

6 0
3 years ago
Give two possible sets of four quantum numbers for the electron in hydrogen when it is in its lowest energy state.
konstantin123 [22]

Answer:

Explanation:

The electron in the lowest energy state will be found in 1 s energy level.

set of 4 possible quantum numbers

Principal quantum no : n = 1 ,

Azimuthal quantum no l = 0

Magnetic quantum no m = 0

Spin quantum no  s = + 1/2

set of other quantum nos

Principal quantum no : n = 1 ,

Azimuthal quantum no l = 0

Magnetic quantum no m = 0

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4 0
2 years ago
The absolute temperature of a gas is increased four times while maintaining a constant volume. What happens to the
weqwewe [10]

Answer:

The pressure increases by a factor of four.

Explanation:

Let's consider a gas at a given temperature and pressure (T₁, P₁). The absolute temperature of a gas is increased four times (T₂ = 4 T₁) while maintaining a constant volume. We can assess the effect on the pressure (P₂) by using Gay Lussac's law.

P₁/T₁ = P₂/T₂

P₂ = P₁ × T₂/T₁

P₂ = P₁ × 4 T₁/T₁

P₂ = 4 P₁

The pressure increases by a factor of four.

4 0
2 years ago
Which of the following is equal to an impulse of 18 units?
dem82 [27]
The answer is force=6, time=3, so C is correct
8 0
3 years ago
Read 2 more answers
a compound is composed of only c h and O. Combustion of a 519 gram sample of the compound yields 1.24 grams of CO2 and?
densk [106]

Answer:

C3H3O

Explanation:

Question incomplete needs to be rewritten:

A compound is composed of only C, H, and O. The combustion of a .519-g sample of the compound yields 1.24g of CO_2 and 0.255 g of H_2 O. What is the empirical formula of the compound

We can get the answer through calculations as follows.

From the mass of carbon iv oxide produced, we can get the number of moles of carbon produced. We first divide the mass by the molar mass of carbon iv oxide. The molar mass of carbon iv oxide is 44g/mol

The number of moles of carbon iv oxide is 1.24/44= 0.0282

Since there is only one carbon atom in CO2, the number of moles of carbon is same as above

The mass of carbon in the compound is simply the number of moles multiplied by the atomic mass unit. The atomic mass unit of carbon is 12. The mass of carbon in the compound is thus 12 * 0.0282= 0.338

From the number of moles of water, we can get the number of moles of hydrogen. To get the number of moles of water, we need to divide the mass of water by its molar mass. Its molar mass is 18g/mol. The number of moles here is thus 0.255/18= 0.0142 moles

But there are 2 atoms of hydrogen in 1 mole of water and thus, the number of moles of hydrogen is 2 * 0.0142= 0.0283

The mass of hydrogen is thus 0.0283 * 1 = 0.0283g

The mass of oxygen equals the mass of the compound minus that of hydrogen and that of carbon.

= 0.519 - 0.338 - 0.0283= 0.1527g

The number of moles of oxygen is the mass of oxygen divided by its atomic mass unit.

That equals 0.1527/16= 0.00954375 moles

The empirical formula can be obtained by dividing the number of moles of each by the smallest which is that oxygen 0.00954375 moles

H = 0.0284/0.00954375 = 2.97 = 3

O = 0.00954375/0.00954375= 1

C = 0.0282/0.00954375 = 2.95 = 3

The empirical formula is thus C3H3O

7 0
3 years ago
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