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3 years ago

Plz help due today!

1 answer:

3 0

Percentage error = ((12.7/11.5)-100%)x 100% = 10.4% (3 s.f.)

Since the measured yield exceeds the theoretical one, this means the error is in excess. Divide the measured yield by the theoretical yield and subtract 100% to find the difference, then multiply by 100% to find the percentage.

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Calculate the ph of a 0.17 m solution of c6h5nh3no3 (kb for c6h5nh2 = 3.8 x 10-10). record your ph value to 2 decimal places.

MatroZZZ [7]

Mass of the solution = 0.17m
Kb for C6H5NH2 = 3.8 x 10^-10
We know Ka for C6H5NH2 = 1.78x10^-11
We have Kw = Ka x Kb => Ka = Kw / Kb
=> (C2H5NH2)(H3O^+)/(C2H5NH3^+) => 1.78x10^-11 = K^2 / 0.17
K^2 = 3 x 10^-12 => K = 1.73 x 10^-6.
pH = -log(Kw(H3O^+)) = -log(1.73 x 10^-6) = 5.76

6 0

3 years ago

How many milligrams of a 20mg sample of cesium-137 remain after 60 years

andrey2020 [161]

Cs -137 has a half life of about 30 years. If 60 years pass, there is two half lives passed so 1/2 * 1/2= 1/4. Take 1/4 and multiply it with the mass given:
(1/4)*20mg=5mg left

5 0

3 years ago

Perform the following mathematical operation and express the results to the correct number of significant figures. (0.102 x 0.08

Kobotan [32]

Answer:

2.26

Explanation:

First you should know what are significant figures,

1 . All non - zero digits are significant.

2 . The zero between two non- zero are significant.Ex 302 has 3 significant figures.

3. The zero before the decimal and before any non-zero digit is non significant. Example : 0.003 has only 1 significant figure.

4. The zero after non zero are non - significant . But the zeros after the decimal point are significant.

300 has only 1 significant figure

300.0 has 4 significant figure

The least number of significant figures present in the number should be there in the final answer of the calculation.

Look at the number having minimum significant digits :

It is 3 (every number has 3- significant figures ) So the answer should also contain 3 - significant figures.

$\frac{0.102\times 0.0821\times 273}{1.01}$

First solve the numerator part

$\frac{2.285}{1.01}$

$=2.2635$

Round off this number to 3 significant figures.

Answer is = 2.26

It has 3 - significant digit since all the digits are non-zero.

5 0

3 years ago

If you heat your melting point tube too quickly, what will your observed melting point be in comparison to the actual melting po

solniwko [45]

Explanation:

When conducting a melting point experiment, if we were to heat a sample quickly. Large amount heat is provided instantly which would melt the crystals in the tube very quickly, even before the temperature of the thermometer reaches to that level. So the observes melting point would be much lower than the actual melting point when sample is heated slowly.

5 0

3 years ago

Insulation is the percentage of energy that is actually used to perform work true or false

Tresset [83]

The answer is false. The correct answer would be efficiency.

4 0

3 years ago

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