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jek_recluse [69]
3 years ago
8

The Ka of a certain indicator is 4 ×10−7. The color of HIn is green and that of In− is red. A few drops of the indicator are add

ed to an HCl solution, which is then titrated against an NaOH solution. Over which pH range will the indicator change color?
Chemistry
1 answer:
Monica [59]3 years ago
4 0

Answer:

7.4 - 5.4.

Explanation:

The relationship between HIn that is the non-ionized form and the In^-; the ionized form is an equilibrium Reaction which is given below;

HIn(aq) + H2O(l) <--------> H3O^+(aq). + In^-(aq).

From the question, we are given that the ka is 4 ×10^−7, therefore, the mathematical relationship between HIn and In^- is given below;

Ka = [H3O^+] [In^-] / [HIn] = 4 ×10^−7.

The formula we are going to be using to solve this question is given below;

pH = pKa (+ or -) 1.

Recall that the relationship between the ka and pKa;

pKa = - log (ka).

pKa = - log ( 4 ×10^−7).

pKa = 6.4

Therefore, for it to have a distinct color change, the pH range will be;

pH = pKa (+ or -) 1.

pH= 6.4 + 1 = 7.4.

pH= 6.4 - 1 = 5.4.

Hence, the pH range = 7.4 - 5.4.

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Which is the smallest number?
My name is Ann [436]

Answer:

What I came up with was D equaling out to be 42

Explanation:

Im assuming you just do the math

A. 3.5 x 104 = 364

B. 2.4 x 103 = 247.2

C. 1.4 x 10^2_2 = 280

D. 4.9 x 10-7 = 42

I hope I helped.

5 0
3 years ago
When aqueous solutions of Na2SO4 and Pb(NO3)2 are mixed, PbSO4 precipitates. Calculate the mass of PbSO4 formed when 1.25 L of 0
neonofarm [45]

Answer:

The mass of PbSO4 formed 15.163 gram

Explanation:

mole of Pb(NO₃)₂ = 1.25 x 0.05 = 0.0625

mole of Na₂SO₄ = 2 x 0.025 = 0.05

                                      Pb(NO₃)₂ + Na₂SO₄ → PbSO₄ + 2 NaNO₃

( Mole/Stoichiometry )    \frac{0.0625}{1}           \frac{0.05}{1}

                                     = 0.0625     = 0.05

From  (Mole/ Stoichiometry ) we can conclude that Na₂SO₄ is limiting reagent.

Mass of PbSO₄ precipitate = 0.05 x Molecular mass of PbSO₄

                                            = 0.05 x 303.26 g

                                            = 15.163 g

7 0
3 years ago
Mendeleev put elements in groups while creating the periodic table. What important role do groups play in the structure of the p
NikAS [45]

Answer:

Groups show similar chemical properties about the elements

Explanation:

The periodic table is divided into groups and periods. Groups are vertical while periods are horizontal.

All elements in the same group possess the same number of outermost shell electrons. This number of outermost shell electrons controls the reactivity of the elements in the group.

Hence, groups show similar chemical properties of the elements in them, Groups separate elements into families which assist in the speedy study of elements.

3 0
3 years ago
2. How many grams of water can be heated from 20.0 oC to 75oC using 12500.0 Joules?
kenny6666 [7]

Answer;

  = 0.054 kg or 54 g

Explanation;

Using the equation; Q = mcΔT where Q is the quantity of heat transferred, m is the mass, c is specific heat of the substance, ΔT is delta T, the change in temperature.  

ΔT = 75 - 20 = 55 C.  

Solve the equation for m  

m = Q/ cΔT

Mass = 12500 / (55 × 4200)

        = 0.054 kg or 54 g


4 0
3 years ago
Read 2 more answers
Hydrogen and chlorine react to form hydrogen chloride, like this:
REY [17]

Answer:

the value of the equilibrium constant Kp for this reaction is 0.275

Explanation:

Step 1: Data given

Pressure HCl at the equilibrium = 18.0 atm

Pressure H2 at the equilibrium = 25.4 atm

Pressure Cl2 at the equilibrium = 46.4 atm

Step 2: The balanced equation

H2(g) + Cl2(g) → 2 HCl(g)

Step 3: Calculate the value of the equilibrium constant Kp for this reaction

Kp = (pHCl)² / (pH2*pCl2)

Kp = 18.0² / (25.4 * 46.4)

Kp = 324 / 1178.56

Kp = 0.275

the value of the equilibrium constant Kp for this reaction is 0.275

3 0
3 years ago
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