2NO(g) + O2 (g) --> 2NO2

A 0.187 M weak acid solution has a pH of 3.99. Find Ka for the acid. Express your answer using two significant figures.

Anna35 [415]

Answer:

5.56 × 10⁻⁸

Explanation:

Step 1: Given data

Concentration of the weak acid (Ca): 0.187 M

pH of the solution: 3.99

Step 2: Calculate the concentration of H⁺

We will use the following expression.

pH = -log [H⁺]

[H⁺] = antilog -pH = antilog -3.99 = 1.02 × 10⁻⁴ M

Step 3: Calculate the acid dissociation constant (Ka)

We will use the following expression.

$Ka = \frac{[H^{+}]^{2} }{Ca} = \frac{(1.02 \times 10^{-4})^{2} }{0.187} = 5.56 \times 10^{-8}$

3 0

3 years ago

Scientific knowledge is open to change as new information is discovered. Which of the following would NOT be a result of new sci

amid [387]

B would be the answer

4 0

4 years ago

Answer the following questions based on the reaction below: NaOH(aq) + KHP(s) --> NaKP(aq)+H2O(I)

Natali [406]

Answer:

a) 1.44g

b) 77.3%

Explanation:

1. Chemical balanced equation (given)

$NaOH(aq)+ KHP(s)\rightarrow NaKP(aq)+H_2O(l)$

2. Mole ratio

$1molNaOH(aq):1molKHP(s)$

This is, 1 mol of NaOH will reacts with 1 mol of KHP.

3. Find the number of moles in 72.14 mL of the base

$Molarity=\text{number of moles of solute}/\text{volume of solution in liters}$

$\text{Volume of solution}=72.14mL=0.07214liters$

$\text{Number of moles of NaOH}=0.0978M\times 0.07214liter=0.007055mol$

4. Find the number of grams of KHP that reacted

The number of moles of KHP that reacted is equal to the number of moles of NaOH, 0.007055 mol

Convert moles to grams:

mass = number moles × molar mass = 0.007055mol × 204.23g/mol

mass = 1.4408 g.

You have to round to 3 significant figures: 1.44 g (because the molarity is given with 3 significant figures).

5. Find the percentage of KHP in the sample

The percentage is how much of the substance is in 100 parts of the sample.

The formula is:

% = (mass of substance / mass of sample) × 100

% = (1.4408g/ 1.864g) × 100 = 77.3%

7 0

3 years ago

Indicate which of the following statements is FALSE.a. Covalent bonds connect nucleotides in a strand; noncovalent interactions

LenaWriter [7]

Answer:

The false statement is d Avery,Macleod and McCarty showed that DNA is the genetic information of cells and RNA is the genetic information in the viruses .

Explanation:

Avery,Macleod and MacCarty showed that DNA is the genetic material of the cell.

On the other hand Fraenkel, Conrat and Sanger carried out their experiment on tobacco mosaic virus to prove that RNA act as genetic material in some viruses.

8 0

4 years ago

A sample of carbon dioxide gas occupies a volume of 250 mL at 25c what volume will it occupy at 95c

anzhelika [568]

Considering the Charles's law, the sample of carbon dioxide gas will occupy 308.72 mL.

<h3>Charles's law</h3>

Charles's law establishes the relationship between the temperature and the volume of a gas when the pressure is constant. This law says that the volume is directly proportional to the temperature of the gas: for a given sum of gas at constant pressure, as the temperature increases, the volume of the gas increases and as the temperature decreases, the volume of the gas decreases.

Mathematically, Charles's law states that the ratio between volume and temperature will always have the same value:

$\frac{V}{T} =k$