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An unknown compound contains only carbon, hydrogen, nitrogen, and oxygen. Complete combustion of a 2.77 g sample of the compound

alisha [4.7K]

The molecular formula of the unknown compound is determined as C₉H₁₁NO₂.

<h3>Molecular formula of the compound</h3>

The molecular formula is calculated as follows;

CHNO + O₂ ------------> CO₂ + H₂O

Mass of carbon, C: = (6.64 x 12)/44 = 1.81 g in 2.77 g sample

Mass of hydrogen, H: = (1.67 x 2)/18 = 0.186 g in 2.77 g sample

Mass of Nitrogen, N: = (2.77 x 0.143)/1.69 = 0.234 g

Mass of oxygen, O: = 2.77 g - 1.81 g - 0.186 g - 0.234 g = 0.54 g

<h3>molar ratio of the elements: </h3>

C = 1.81 g = 0.15 mol

H = 0.186 g = 0.186 mol

N = 0.234 g = 0.017 mol

O = 0.54 g = 0.0337 mol

divide through with the smallest number of moles (0.017 mol);

C = 9

H = 11

N = 1

O = 2

Molecular formula = C₉H₁₁NO₂

Check the molar mass of the compound = (9 x 12) + (11 x 1) + (14) + (2 x 16) = 165 g/mol

Thus, the molecular formula of the unknown compound is determined as C₉H₁₁NO₂.

Learn more about molecular mass here: brainly.com/question/21334167

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4 0

2 years ago

Explain the term contact force and give examples

aliya0001 [1]

Answer & Explanation:

In physics, a contact force is a force that acts at the point of contact between two objects, in contrast to body forces. Contact forces are described by Newton's laws of motion, as with all other forces in dynamics. Contact force is the force in which an object comes in contact with another object. Contact forces are also direct forces. Contact forces are ubiquitous and are responsible for most visible interactions between macroscopic collections of matter. Pushing a car up a hill or kicking a ball or pushing a desk across a room are some of the everyday examples where contact forces are at work. In the first case the force is continuously applied by the person on the car, while in the second case the force is delivered in a short impulse.

3 0

3 years ago

A student balanced the chemical equation Mg + O2 →MgO by writing Mg + O2 → MgO2. Was the equation balanced correctly? Explain yo

Amanda [17]

Explanation:

Charges on both magnesium and oxygen is 2. Though opposite in sign, they have equal charges so, both of them will be cancelled by each other.

As a result, formula of magnesium oxide is MgO and not $MgO_{2}$ .

The student write the equation as $Mg + O_2 \rightarrow MgO_2$ , it is not correct.

Therefore, given equation will be balanced as follows.

$2Mg + O_{2} \rightarrow 2MgO$

Since, number of atoms on both reactant and product side are equal. Hence, this equation is completely balanced.

7 0

3 years ago

What is the pH of 0.000134 M solution of HCI?

mafiozo [28]

Answer: The pH will be 3.87

Explanation:

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

$pH=-\log [H^+]$

$HCl\rightarrow H^++Cl^{-}$

According to stoichiometry,

1 mole of $HCl$ gives 1 mole of $H^+$

Thus $0.000134$ moles of $HCl$ gives = $\frac{1}{1}\times 0.000134=0.0001342$ moles of $H^+$

Putting in the values:

$pH=-\log[0.000134]$

$pH=3.87$

Thus the pH will be 3.87

5 0

3 years ago

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What is the pH difference of two samples if the concentration of [H+] ions is 1000-fold less in the second sample?

snow_tiger [21]

The correct answer is a. This is because the pH of a solution is defined as -log10(concentration of H+ ions). An inverse logarithmic scale such as this means that a solution with a lower concentration of H+ ions will have a higher pH than one with a higher concentration. Therefore we know that the pH of the second sample will be higher than the first.

Since the logarithmic scale has the base 10, a change by 1 on the scale is a consequence of multiplication/division of the H+ concentration by a factor of 10. As the scale is inverse, this means that a decrease of concentration by factor 1000 is equivalent to increasing the pH by (1000/10) = 3.

4 0

3 years ago

Read 2 more answers