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love history [14]
3 years ago
15

A certain amount of hydrogen peroxide was dissolved in 100. mL of water and then titrated with 1.68 M KMnO4. What mass of H2O2 w

as dissolved if the titration required 21.3 mL of the KMnO4 solution
Chemistry
1 answer:
Stels [109]3 years ago
8 0

Answer:

see explanation below

Explanation:

First to all, this is a redox reaction, and the reaction taking place is the following:

2KMnO4 + 3H2SO4 + 5H2O2 -----> 2MnSO4 + K2SO4 + 8H2O + 5O2

According to this reaction, we can see that the mole ratio between the peroxide and the permangante is 5:2. Therefore, if the titration required 21.3 mL to reach the equivalence point, then, the moles would be:

MhVh = MpVp

h would be the hydrogen peroxide, and p the permanganate.

But like it was stated before, the mole ratio is 5:2 so:

5MhVh = 2MpVp

Replacing moles:

5nh = 2MpVp

Now, we just have to replace the given data:

nh = 2MpVp/5

nh = 2 * 1.68 * 0.0213 / 5

nh = 0.0143 moles

Now to get the mass, we just need the molecular mass of the peroxide:

MM = 2*1 + 2*16 = 34 g/mol

Finally the mass:

m = 0.0143 * 34

m = 0.4862 g

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Gre4nikov [31]

The specific heat capacity of the given substance is -0.66 J/g°C.

<u>Explanation:</u>

The heat absorbed by any substance is the product of its mass, specific heat capacity and change in temperature.

q = m × c × ΔT

m is the mass in grams

q = amount of heat released or absorbed in J

ΔT = change in temperature in °C = 5 -50 = -45°C

c = specific heat capacity in J/g°C

c = $\frac{q}{m \times dT}

Plugin the values, we will get,

c = $\frac{2192 }{73.9 \times-45}

= -0.66 J/g°C

3 0
3 years ago
Beth’s hygrometer is reading a temperature of 30°C and a relative humidity of 65%. The humidity in the air is how many grams/cub
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If you initially have a volume of 4 L and a temperature of 300K. Then you decreased the volume to 2 L, what is the new temperatu
ASHA 777 [7]

Answer:

T₂ = 150 K

Explanation:

Given data:

Initial volume = 4 L

Initial temperature = 300 K

Final volume = 2 L

Final temperature = ?

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

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T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

T₂ = T₁V₂/V₁  

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3 years ago
The p-value of a statistical test depends on all of the following, except:
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Answer:

The correct option is e.

Explanation:

p-value is the probability value for a given statistical model, the probability that, when the null hypothesis is true.

For two two samples the formula of test statistics is

t=\frac{(\overline{x}_1-\overline{x}_2)-(\mu_1-\mu_2)}{\sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2}}}

where,

\overline{x} is sample mean

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s is standard deviation.

n is sample size.

Variance is the square of standard deviation.

It means variance, mean, numbers of samples is used in calculation of p-value.

Degree of freedom define the shape of the t-distribution that your t-test uses to calculate the p-value.

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4 0
3 years ago
4. A student purified a 500-mg sample of phthalic acid by recrystallization from water. The published solubility of phthalic aci
kupik [55]

Answer:

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Explanation:

We know from the problem that 18 g of phthalic acid are dissolved in 100 mL of water at 99 °C.

Now we devise the following reasoning:

If          18 g of phthalic acid are dissolved in 100 mL of water at 99 °C

Then   0.5 g of phthalic acid are dissolved in X mL of water at 99 °C

X = (0.5 × 100) / 18 = 2.77 mL of water

7 0
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