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Contact [7]
3 years ago
9

A 5.024 mg sample of an unknown organic molecule containing carbon, hydrogen, and nitrogen only was burned and yielded 13.90 mg

of CO2 and 6.048 mg of H2O. What is the empirical formula
Chemistry
1 answer:
Dafna1 [17]3 years ago
8 0

Answer:

C8H17N

Explanation:

Mass of the unknown compound = 5.024 mg

Mass of CO2 = 13.90 mg

Mass of H2O = 6.048 mg

Next, we shall determine the mass of carbon, hydrogen and nitrogen present in the compound. This is illustrated below:

For carbon, C:

Molar mass of CO2 = 12 + (2x16) = 44g/mol

Mass of C = 12/44 x 13.90 = 3.791 mg

For hydrogen, H:

Molar mass of H2O = (2x1) + 16 = 18g/mol

Mass of H = 2/18 x 6.048 = 0.672 mg

For nitrogen, N:

Mass N = mass of unknown – (mass of C + mass of H)

Mass of N = 5.024 – (3.791 + 0.672)

Mass of N = 0.561 mg

Now, we can obtain the empirical formula for the compound as follow:

C = 3.791 mg

H = 0.672 mg

N = 0.561 mg

Divide each by their molar mass

C = 3.791 / 12 = 0.316

H = 0.672 / 1 = 0.672

N = 0.561 / 14 = 0.040

Divide by the smallest

C = 0.316 / 0.04 = 8

H = 0.672 / 0.04 = 17

N = 0.040 / 0.04 = 1

Therefore, the empirical formula for the compound is C8H17N

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In a redox reaction, how does the total number of electrons lost by the oxidized substance compare to the total number of electr
snow_lady [41]
The answer is (2) equal to. In redox reactions, you can't just lose electrons somewhere. If an electrons is lost by one, it must be gained by another. Hence, the importance of balancing redox reactions.
3 0
3 years ago
A titration of 25.0 mL of a solution of the weak base aniline, C6H5NH2, requires 25.67 mL of 0.175 M HCl to reach the equivalenc
Lorico [155]

Answer:

a. 0.180M of C₆H₅NH₂

b. 0.0887M C₆H₅NH₃⁺

c. pH = 2.83

Explanation:

a. Based in the chemical equation:

C₆H₅NH₂(aq) + HCl(aq) → C₆H₅NH₃⁺(aq) + Cl⁻(aq)

<em>1 mole of aniline reacts per mole of HCl</em>

Moles required to reach equivalence point are:

Moles HCl = 0.02567L ₓ (0.175mol / L) = 4.492x10⁻³ moles HCl = moles C₆H₅NH₂

As the original solution had a volume of 25.0mL = 0.0250L:

4.492x10⁻³ moles C₆H₅NH₂ / 0.0250L = 0.180M of C₆H₅NH₂

b. At equivalence point, moles of C₆H₅NH₃⁺ are equal to initial moles of C₆H₅NH₂, that is 4.492x10⁻³ moles

But now, volume is 25.0mL + 25.67mL = 50.67mL = 0.05067L. Thus, molar concentration of C₆H₅NH₃⁺ is:

[C₆H₅NH₃⁺] = 4.492x10⁻³ moles / 0.05067L = 0.0887M C₆H₅NH₃⁺

c. At equivalence point you have just 0.0887M C₆H₅NH₃⁺ in solution. C₆H₅NH₃⁺ has as equilibrium in water:

C₆H₅NH₃⁺(aq) + H₂O(l) → C₆H₅NH₂ + H₃O⁺

Where Ka = Kw / Kb = 1x10⁻¹⁴ / 4.0x10⁻¹⁰ =

<em>2.5x10⁻⁵ = [C₆H₅NH₂] [H₃O⁺] / [C₆H₅NH₃⁺]</em>

When the system reaches equilibrium, molar concentrations are:

[C₆H₅NH₃⁺] = 0.0887M - X

[C₆H₅NH₂] = X

[H₃O⁺] = X

Replacing in Ka formula:

2.5x10⁻⁵ = [X] [X] / [0.0887M - X]

2.2175x10⁻⁶ - 2.5x10⁻⁵X = X²

0 = X² + 2.5x10⁻⁵X - 2.2175x10⁻⁶

Solving for X:

X = -0.0015 → False solution. There is no negative concentrations.

X = 0.001477 → Right solution.

As [H₃O⁺] = X, [H₃O⁺] = 0.001477

Knowing pH = -log [H₃O⁺]

pH = -log 0.001477

<h3>pH = 2.83</h3>

7 0
2 years ago
NASA communicates with the Space Shuttle and International Space Station using Ku-band microwave radio. Suppose NASA transmits a
Margarita [4]

Answer:

λ = 0.0167 m = 16.7 mm

Explanation:

The wavelength of these radio waves can be found out by using the formula for the speed of radio waves:

v = fλ

where,

v = speed of radio waves = speed of light = 3 x 10⁸ m/s

f = frequency of radio waves = 18 GHz = 18 x 10⁹ Hz

λ = Wavelength = ?

Therefore,

3 x 10⁸ m/s = (18 x 10⁹ Hz)λ

λ = (3 x 10⁸ m/s)/(18 x 10⁹ Hz)

<u>λ = 0.0167 m = 16.7 mm</u>

4 0
2 years ago
b) If 1.5 mole of oxygen reacted, how many mole of iron (III) oxide would be formed from the reaction?
lyudmila [28]

Answer:

If there reacted 1.5 moles of O2, there will be produced 1.0 mol of Fe2O3

Explanation:

Step 1: Data given

Number of moles oxygen reacted = 1.5 moles

Step 2: The balanced equation

4Fe + 3O2 → 2Fe2O3

Step 3: Calculate moles of Fe2O3

For 4 moles Fe consumed, we need 3 moles of O2 to produce 2 moles of Fe2O3

For 1.5 moles O2 consumed, we'll have 2/3 * 1.5 = 1.0 mol of Fe2O3

If there reacted 1.5 moles of O2, there will be produced 1.0 mol of Fe2O3

7 0
3 years ago
Calculate the mass of oxygen in 30 g of CH NH COOH?​
Naya [18.7K]

Molar mass of CH2NH2COOH - 75

Given mass of CH2NH2COOH - 30

Moles of CH2NH2COOH = Given mass/ Molar mass

moles of CH2NH2COOH = 30/75 = 0.4 mol

One mole of CH2NH2COOH contains 32 gram of oxygen

0.4 mole of CH2NH2COOH will contain = 0.4 × 32= 12.8 g of oxygen

Answer- the mass of oxygen in 30 g of CH2NH2COOH is 12.8 gram!

7 0
2 years ago
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