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1 year ago

Calculate the Ph and the POH of an aqueous solution that is 0. 040 m in HCl(aq) and 0. 075 m in HBr(aq) at 25 °C.

1 answer:

5 0

pH is the measure of the hydrogen ion concentration while pOH is of hydroxide ion concentration in the solution. The pH is 0.939 and pOH is 13.061 pOH.

pH is the concentration of the hydrogen ion released or gained by the species in the solution that depicts the acidity and basicity of the solution.

pOH is the concentration of the hydroxide ion in the solution and is dependent on the pH as an increase in pH decreases the pOH and vice versa.

Both HCl and HBr are strong acids and gets ionized 100 % in the solution. If we let 1 L of solution for the acids then the concentration of the hydrogen ion will be 0.100 M.

Since both completely dissociate we would just add the molarities of each of the H+ ions together and then calculate the PH and POH from that :

HCL(0.040M)----> H+(0.040M) +CL-(0.040M)

HBr(0.075M)----> H+(0.075M) +Br-(0.075M)

so 0.040M (H+ from HCL) + 0.075M (H+ from HBr) = 0.115M H+ in total.

pH is calculated as:

pH = -log[H+]

Substituting values in the equation:

log(0.115M)= 0.939 pH

pOH is calculated as:

14 - pH = pOH

Substituting values in the equation above:

14 - 0.939= 13.061 pOH

Therefore, pH is 0.939 and pOH is 13.061.

Learn more about pH and pOH here:

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When a 2.00 g sample of KCl is dissolved in water in a calorimeter that has a total heat capacity of 1.28 kJ ⋅ K − 1 , the tempe

Alchen [17]

Answer : The molar heat of solution of KCl is, 17.19 kJ/mol

Explanation :

First we have to calculate the heat of solution.

$q=c\times (\Delta T)$

where,

q = heat produced = ?

c = specific heat capacity of water = $1.28kJ/K$

$\Delta T$ = change in temperature = 0.360 K

Now put all the given values in the above formula, we get:

$q=1.28kJ/K\times 0.360K$

$q=0.4608kJ=460.8J$

Now we have to calculate the molar heat solution of KCl.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat released = 460.8 J

m = mass of $KCl$ = 2.00 g

Molar mass of $KCl$ = 74.55 g/mol

$\text{Moles of }KCl=\frac{\text{Mass of }KCl}{\text{Molar mass of }KCl}=\frac{2.00g}{74.55g/mole}=0.0268mole$

Now put all the given values in the above formula, we get:

$\Delta H=\frac{460.8J}{0.0268mole}$

$\Delta H=17194.029J/mol=17.19kJ/mol$

Therefore, the molar heat of solution of KCl is, 17.19 kJ/mol

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2 years ago

In the flame test, barium ions produce a green flame whereas calcium ions produce a red flame. In your own words, explain these

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Answer:

The Barium flame is green because it is a difficult flame to excite, therefore for it to trigger a flame it is necessary that it be too excited for it to occur.

The reddish color of calcium is due to its high volatility and it is sometimes very difficult to differentiate it from strontium.the compression of these elements is due to being able to make them work during combustion

Explanation:

The flame test is a widely used qualitative analysis method to identify the presence of a certain chemical element in a sample. To carry it out you must have a gas burner. Usually a Bunsen burner, since the temperature of the flame is high enough to carry out the experience (a wick burner with an alcohol tank is not useful). The flame temperature of the Bunsen burner must first be adjusted until it is no longer yellowish and has a bluish hue to the body of the flame and a colorless envelope. Then the tip of a clean platinum or nichrome rod (an alloy of nickel and chromium), or failing that of glass, is impregnated with a small amount of the substance to be analyzed and, subsequently, the rod is introduced into the flame, trying to locate the tip in the least colored part of the flame.

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At a macroscopic level, it is observed that the sample, when heated in the flame, will provide a characteristic color to it. For example, if the tip of a rod is impregnated with a drop of Ca2 + solution (the previous notation indicates that it is the calcium ion, that is, the calcium atom that has lost two electrons), the color observed is brick red .

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How many moles are in 24.75 g of H2O? What is given the conversation and the unknown?

riadik2000 [5.3K]

Answer:

1.373 mol H₂O

General Formulas and Concepts:

Chemistry - Atomic Structure

Reading a Periodic Table
Using Dimensional Analysis

Explanation:

Step 1: Define

24.75 g H₂O

Step 2: Identify Conversions

Molar Mass of H - 1.01 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H₂O - 2(1.01) + 16.00 = 18.02 g/mol

Step 3: Convert

$24.75 \ g \ H_2O(\frac{1 \ mol \ H_2O}{18.02 \ g \ H_2O} )$ = 1.37347 mol H₂O

Step 4: Check

We are given 4 sig figs. Follow sig fig rules and round.

1.37347 mol H₂O ≈ 1.373 mol H₂O

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