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3 years ago

Someone please help me

Chemistry

1 answer:

Setler79 [48]3 years ago

5 0

Answer:

8510 mol

Explanation:you must divide both of the molar masses into each other

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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

Which statement must be true for any chemical reaction at equilibrium?

sergejj [24]

<span>The correct answer is 3. The concentration of the product and the concentration of the reactants are equal. That is because matter cannot be created or destroyed and the product cannot randomly become something else in the reaction, nor can a reactant change into something different. Simply put, you cannot turn things like water into gold because there will always be an equilibrium.</span>

4 0

4 years ago

Read 2 more answers

What is the concentration of ammonia in a solution if 23.4 mL of a 0.117 M solution of HCl are needed to titrate a 100.0 mL samp

Georgia [21]

Answer: 0.0274 M

Explanation:-

The balanced chemical solution is:

$NH_4OH(aq)+HCl(aq)\rightarrow NH_4Cl(aq)+H_2O(l)$

According to the neutralization law,

$n_1M_1V_1=n_2M_2V_2$

where,

$M_1$ = molarity of $HCl$ solution = 0.117 M

$V_1$ = volume of $HCl$ solution = 23.4 ml

$M_2$ = molarity of $NH_4OH$ solution = ?

$V_2$ = volume of $NH_4OH$ solution = 100.0 ml

$n_1$ = valency of $HCl$ = 1

$n_2$ = valency of $NH_4OH$ = 1

$1\times 0.117M\times 23.4=1\times M_2\times 100.0$

$M_2=0.0274$

Therefore, the concentration of ammonia in a solution will be 0.0274 M

8 0

3 years ago

How many element does this element have calcium?

liq [111]

Can you please reword that? I don't understand the question. But I can help you though, I am good at science.

7 0

4 years ago

Which of the following statements is true about the relationships between photon energy, wavelength, and frequency?

iris [78.8K]

Answer: The Answer is A.

Explanation:

The amount of energy is directly proportional to the photon's electromagnetic frequency and thus, equivalently, is inversely proportional to the wavelength. The higher the photon's frequency, the higher its energy. Equivalently, the longer the photon's wavelength, the lower its energy.

Hope this Helps!

8 0

4 years ago