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zvonat [6]
3 years ago
12

HELP PLEASE I GIVE 21 POINTS!!!! +BRAINLIEST!!!!!!!

Chemistry
2 answers:
Maslowich3 years ago
8 0
There was a noise in my closet one night and it creeped me out. It scared me until I told myself that it might not be so scary if I checked it out. When I got to the closet, my heart pounding, I realized that it was just a book that had fallen off the shelf. 
cricket20 [7]3 years ago
7 0
You could write about a fear you may have had as a child, eg. the dark, or underneath the bed, etc...
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Which statement best describes London dispersion forces?
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3 years ago
Caffeine, a stimulant in coffee and tea, has a molar mass of 194.19 g/mol and a mass percentage composition of 49.48% C, 5.19% H
lozanna [386]

Answer : The molecular formula of a caffeine is, C_8H_{10}N_4O_2

Solution :

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 49.48 g

Mass of H = 5.19 g

Mass of N = 28.85 g

Mass of O = 16.48 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of N = 14 g/mole

Molar mass of O = 16 g/mole

Step 1 : convert given masses into moles.

Moles of C = \frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{49.48g}{12g/mole}=4.12moles

Moles of H = \frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{5.19g}{1g/mole}=5.19moles

Moles of N = \frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{28.85g}{14g/mole}=2.06moles

Moles of O = \frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{16.48g}{16g/mole}=1.03moles

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = \frac{4.12}{1.03}=4

For H = \frac{5.19}{1.03}=5.03\approx 5

For N = \frac{2.06}{1.03}=2

For O = \frac{1.03}{1.03}=1

The ratio of C : H : N : O = 4 : 5 : 2 : 1

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula = C_4H_5N_2O_1=C_4H_5N_2O

The empirical formula weight = 4(12) + 5(1) + 2(14) + 16 = 97 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

n=\frac{\text{Molecular formula}}{\text{Empirical formula weight}}

n=\frac{194.19}{97}=2

Molecular formula = (C_4H_5N_2O)_n=(C_4H_5N_2O)_2=C_8H_{10}N_4O_2

Therefore, the molecular of the caffeine is, C_8H_{10}N_4O_2

5 0
3 years ago
How much °f of 35°C ? <br>help me please<br>​
MakcuM [25]

Answer: 95 degrees fahrenheit hope this helps :]

Explanation:

6 0
3 years ago
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