All categories

3 years ago

Which process is an example of a physical change?

1 answer:

3 0

The process that is an example of a chemical change would be of ice turning into water when heated over a Bunsen Burner.

You might be interested in

Lead (II)oxide+calcium metal=

AfilCa [17]

I didn’t understand

3 0

2 years ago

Why is it better to allow the solvent front to move almost to the top of a paper strip rather than stopping it at the halfway po

m_a_m_a [10]

Answer:

To allow all the elements or compounds to separate complete.

Explanation:

In chromatography, the compounds need some space and time to separate, one from each other, if you just use the half of the paper strip maybe you will not notice the different spots of compounds. Remember all the substances have different affinity for the solvents, that means, some react very quickly but others need more time as the colors that conform the black color in an ink.

4 0

2 years ago

Which is not an important property of metal?

lukranit [14]

The answer is D solubility

hope this helps:)

3 0

3 years ago

Read 2 more answers

A 45g Aluminum spoon (specific heat 0.88J/g degree Celcius) at 24 degrees Celcius placed in 180ml(180g) of coffee at 85 degrees

yarga [219]

Answer:

82 °C

Explanation:

Let the specific heat capacity of the coffee be that of water which is 4.2 J/g °C.

Now, at the final temperature, heat gained by Aluminum spoon ,Q equals heat lost by coffee, Q'.

Q = -Q'

Q = m₁c₁(T₂ - T₁) where m₁ = mass of aluminum spoon = 45 g, c₁ = specific heat of aluminum = 0.88 J/g °C, T₁ = initial temperature of aluminum spoon = 24 °C and T₂ = final temperature of aluminum spoon.

Q' = m₂c₂(T₂ - T₃) where m₂ = mass of coffee = 180 g, c₂ = specific heat of coffee = 4.2 J/g °C, T₃ = initial temperature of coffee = 85 °C and T₂ = final temperature of coffee.

So, Q = -Q'

m₁c₁(T₂ - T₁) = -m₂c₂(T₂ - T₃)

Making T₂ subject of the formula, we have

m₁c₁T₂ - m₁c₁T₁ = -m₂c₂T₂ + m₂c₂T₃

m₁c₁T₂ + m₂c₂T₂ = m₂c₂T₃ + m₁c₁T₁

(m₁c₁ + m₂c₂)T₂ = m₂c₂T₃ + m₁c₁T₁

T₂ = (m₂c₂T₃ + m₁c₁T₁)/(m₁c₁ + m₂c₂)

substituting the values of the variables into the equation, we have

T₂ = (180 g × 4.2 J/g °C × 85 °C + 45 g × 0.88 J/g °C × 24 °C )/(45 g × 0.88 J/g °C + 180 g × 4.2 J/g °C)

T₂ = (64260 J + 950.4 J)/(39.6 J/°C + 756 J/°C)

T₂ = 65210.4 J/795.6 J/°C

T₂ = 81.96 °C

T₂ ≅ 82 °C

8 0

3 years ago

Given the 1H and 13C data below, which isomers of C8H11N fit the spectral data? 13C NMR: δ 17.2, 20.4, 115.1, 122.4, 137.3, 127.

iogann1982 [59]

Complete Question

The complete question is shown on the first , second , third and fourth

Answer:

The compound that fit the spectra data are compound B, E and H as shown in the question

Explanation:

From the question we are given that the 13C NMR data is

13C $NMR: 17.2,20.4,115.1,122.4,137.3,127.6,131.1,142.1$ pmm

From the spectral diagram on the question we can see that the signal at 17.2 ppm and 20.4 ppm indicates the presence of two different $sp^{3}$ carbon atoms.

Also the signals at 115.1 , 122.4 , 137.3, 127.6,131.1,142.1 ppm indicates the molecule with six different $sp^{2}$ carbon atoms.

Thus , the compound with two different $sp^{3}$ carbon atoms and six different $sp^{2}$ carbon atoms are shown on the third uploaded image

Now let us take a look at the 1H NMR as follows

For NMR spectra the integration values are in the ration 1.99:1.00:2.19: 5.93

Now we can look at this above ratio like this 2:1:2:6 by reduction

Hence the relative number of proton is in the ratio of 2H: 1H: 2H: 6H

2H at 6-7 ppm and 1H at 6-7 ppm are due to the presence of three aromatic proton which are present on the benzene ring.

2H at 3.5 ppm are due to proton in amino group $NH_{2}$ protons.

6H gives two signals at 2.2 ppm due to the presence of the two $CH_{3}$ protons

The compound A is not matched with 1 H NMR spectra, thus remove the compound A .The other compounds are B,E,F

Thus ,the compound with the proton in the ratio 2H : 1H :2H : 6H are shown on the fourth uploaded image

Hence the compounds with the given NMR spectra are B,E and H

4 0

2 years ago