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4 years ago

Why is the mixture of the titration of potassium permanganate solution using oxalic acid heated before titration?

2 answers:

7 0

The mixture of the titration of potassium permanganate solution using oxalic acid heated before titration to make the temperature optimum for the reaction to take place.

Explanation:

The optimum temperature for reaction of and oxalic acid is 60-70 degree Celsius

If the temperature is low, then the reaction between will be too slow.

If temperature is above optimum then oxalic acid decomposes to give CO2

Under optimum temperature, the reactants receive enough activation energy to start the reaction

If the mixture is heated, due to increased kinetic energy of particles effective collision will take place.

This will increase the rate of reaction.

alexgriva [62]4 years ago

4 0

Explanation:

During titration of oxalic acid and $KMnO_4$ in acid medium to reaction is extremely slow. Since $KMnO_4$ is acting as a self indicator the colour disappears after less than 30s even after approaching equivalent point. So the reaction mixture is heated to approximately 70– $80^0 C$ (just before it starts boiling) and the titration is started. This helps in initiating the reaction via supplying the necessary activation energy of the reaction. Secondly the heat helps to decompose $[Mn(C_2O_4)^3]^{-3}$ complex which forms as a result of local excess of $KMnO_4$ .the complex is unstable above $60^0C$ and the $Mn^{+2}$ formed as a result catalyses the rest of the reaction. Thirdly the temp should never exceed the range given as oxalic acid will decompose above this temp to $Co_2$

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100.0 mL of 3.8M NaCN, the minimum lethal concentration of sodium cyanide in blood serum

9966 [12]

The given question is incomplete. The complete question is:

Calculate the number of moles and the mass of the solute in each of the following solution: 100.0 mL of 3.8 × 10−5 M NaCN, the minimum lethal concentration of sodium cyanide in blood serum

Answer: The number of moles and the mass of the solute are $0.38\times 10^{-5}$ and $18.62\times 10^{-5}g$ respectively

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n = moles of solute

$V_s$ = volume of solution in ml

$3.8\times 10^{-5}M=\frac{n\times 1000}{100.0}$

$n=0.38\times 10^{-5}$

n = moles of $NaCN$ = $\frac{\text {given mass}}{\text {Molar mass}}$

$0.38\times 10^{-5}=\frac{x}{49g/mol}$

$x=18.62\times 10^{-5}g$

Thus the number of moles and the mass of the solute are $0.38\times 10^{-5}$ and $18.62\times 10^{-5}g$ respectively

6 0

3 years ago

“Sugar will dissolve faster in cold water than in hot water.” Is this statement true or false? EXPLAIN using evidence from past

Mice21 [21]

Answer:

false

Explanation:

6 0

3 years ago

Read 2 more answers

THIS IS URGENT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Pani-rosa [81]

Answer:

1- 1.54 mol.

2- 271.9 kPa.

3- Yes, the tires will burst.

4- 235.67 kPa.

5- As, the temperature increased, the no. of molecules that has minimum kinetic energy increases as shown in image 1 that represents the Maxwell’s Distribution of Speeds of molecules. "Kindly, see the explanation and the attached images".

Explanation:

Q1- How many moles of nitrogen gas are in each tire?

To calculate the no. of moles of nitrogen gas in each tire, we can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the nitrogen gas (P = 247.0 kPa/101.325 = 2.44 atm),

V is the volume of the nitrogen gas (V = 15.2 L),

n is the no. of moles of the nitrogen gas (n = ??? mole),

R is the general gas constant (R = 0.082 L.atm/mol.K),

T is the temperature of the nitrogen gas (T = 21°C + 273 = 294 K).

∴ n = PV/RT = (2.44 atm)(15.2 L)/(0.082 L/atm/mol.K)(294.0 K) = 1.54 mol.

Q2: What would the maximum tire pressure be at 50 degrees C?

Now, the temperature is raised to be 50°C (T = 50°C + 273 = 323 K).

The pressure can be calculated using the general gas law: PV = nRT.

∴ P = nRT/V = (1.54 atm)(0.082 L/atm/mol.K)(323.0 K)/(15.2 L) = 2.68 atm = 271.9 kPa.

Q3: Will the tires burst in Moses Lake? Explain.

Yes, the tires will burst because the internal pressure be 271.9 kPa that exceeds 270 kPa, the pressure above which the tires will burst.

Q4: If you must let nitrogen gas out of the tire before you go, to what pressure must you reduce the tires before you start your trip? (Assume no significant change in tire volume.)

To get the pressure that we must begin with:

Firstly, we should calculate the no. of moles at:

T = 55°C + 273 = 328 K,

Pressure = 270 kPa (the pressure above which the tires will burst). (P =270 kPa/101.325 = 2.66 atm).

V = 15.2 L, as there is no significant change in tire volume.

∴ n = PV/RT = (2.66 atm)(15.2 L)/(0.082 L.atm/mol.K)(328 K) = 1.5 mol.

1.5562 moles of N₂ in the tires will give a pressure of 270 kPa at 55°C, so this is the minimum moles of N₂ that will make the tires burst.

Now, we can enter this number of moles into the original starting conditions to tell us what pressure the tires will be at if we start with this number of moles of N₂.

P = ???

V = 15.6 L.

n = 1.5 mol

T = 21°C + 273 = 294.0 K

R = 0.0821 L.atm/mol.K.

∴ P = nRT/V = (1.5 mol x 0.082 x 294.0 K) / (15.6 L) = 2.2325 atm = 235.67 kPa.

So, the starting pressure needs to be 235.67 kPa or just under in order for the tires not to burst.

Q5: Create a drawing of the tire and show a molecular view of the air molecules in the tire at 247 kpa vs the molecular view of the air molecules after the tires have been heated. Be mindful of the number of molecules that you use in your drawing in the before and after scenarios. Use a caption to describe the average kinetic energy of the molecules in both scenarios.

As, the temperature increased, the no. of molecules that has minimum kinetic energy increases as shown in “image 1” that represents the Maxwell’s Distribution of Speeds of molecules.

The no. of molecules that possess a critical K.E. of molecules increases due to increasing the temperature activate the motion of molecules with high velocity as

(K.E. = 3RT/2), K.E. directly proportional to the temperature of the molecules (see image 2).

Also, the average speed of molecules increases as the K.E of the molecules increases (see image 3).

3 0

3 years ago

In the fall, how does the high pressure area affect the hurricane?

tangare [24]

Answer:

Hurricanes occur when ocean water warms during the spring, summer and early fall.

Explanation:

Warm air just above the water’s surface rises. The rising warm air creates a reduction in pressure at the surface, what meteorologists call a low-pressure area. Because nearby air is at a higher pressure, it will flow into the low-pressure zone.

https://www.sidmartinbio.org/how-does-a-high-pressure-system-affect-a-hurricane/

3 0

3 years ago

Which of the following elements would be the least likely to form a cation if involved in a chemical reaction?

quester [9]

Cation means postive charged
answer is potassium.
being +1

6 0

3 years ago

Read 2 more answers

Why is the mixture of the titration of potassium permanganate solution using oxalic acid heated before titration? ​

Why is the mixture of the titration of potassium permanganate solution using oxalic acid heated before titration?