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3 years ago

The reaction of 11.9 g of chcl3 with excess chlorine produced 11.2 g of ccl4, carbon tetrachloride: what is the percent yield?

2 answers:

7 0

73.0% First, lookup the atomic weights of the elements involved Atomic weight carbon = 12.0107 Atomic weight chlorine = 35.453 Atomic weight hydrogen = 1.00794 Calculate the molar masses. Molar mass CHCl3 = 12.0107 + 1.00794 + 3 * 35.453 = 119.37764 Molar mass CCl4 = 12.0107 + 4 * 35.453 = 153.8227 Calculate the number of moles we have Moles CHCl3 = 11.9 g / 119.37764 g/mol = 0.099683659 mol Moles CCl4 = 11.2 g / 153.8227 g/mol = 0.0728111 mol Since with 100% yield, each molecule of CHCl3 should produce one molecule of CCl4, divide the actual moles produced by the number of moles expected for 100% yield. So 0.0728111 / 0.099683659 = 0.730421623 = 73.0421623 % Rounding to 3 significant figures gives 73.0%

Paha777 [63]3 years ago

3 0

First, we need to calculate the theoretical yield as follows:
The balanced chemical reaction is:
2CHCl3 +2Cl2 ----> 2CCl4 +2HCl
molar mass of CHCl3 = 119.378 grams
molar mass of CCl4 = 153.823 grams
number of moles = mass / molar mass = 11.9 / 119.378 = 0.0997 moles
From the balanced equation, 2 moles of CHCl3 produce 2 moles of CCl4.
Therefore, 0.0997 moles of CHCl4 will produce 0.0997 moles of CCl4.
number of moles = mass / molar mass
mass (theoretical) = molar mass * number of moles
mass (theoretical) = 153.823 * 0.0997 = 15.336 grams

Now, we will calculate the percent yield as follows:
% yield = (actual mass / theoretical mass) * 100
% yield = (11.2 / 15.336) * 100 = 73.03%

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Indicate which solution in each pair has the lower pH. Your response should be a four letter "word". The first letter should be

JulijaS [17]

Answer:

bcfh

Explanation:

HClO₄ reacts with water thus:

HClO₄ + H₂O → H₃O⁺ + ClO₄⁻

That means HClO₄ produce H₃O⁺ that decreases pH. That means the higher concentration of HClO₄ decreases pH. Thus, lower pH will be:

b) 0.2 M HClO4

The reaction of NaClO₄ is:

NaClO₄ + H₂O → OH⁻ + HClO₄ + Na⁺

The higher concentration of NaClO₄ the higher production of OH⁻ that increase pH, that means the lower concentration of NaClO₄ the lower pH, thus, the answer is:

c) 0.1 M NaClO or

HF reacts with water thus;

HF ⇄ H⁺ + F⁻

The equilibrium constant is:

k = [H⁺] [F⁻] / [HF] = 3,5x10⁻⁴

For HNO₂ equilibrium is:

HNO₂ ⇄ H⁺ + NO₂⁻

k = [H⁺] [NO₂⁻] / [HNO₂] = 4,5x10⁻⁴

As k value is higher for HNO₂, the concentration of H⁺ will be higher in this system doing the HNO₂ with the lower pH.

f) 0.1 M HNO2

NaOH is a strong base that produce OH⁻ that increase pH, pure water is neutral, thus, the lowe pH is:

h) pure water

I hope it helps!

7 0

3 years ago

If the volume of a gas container at 32 degrees Celsius changes from 1.55 L to 755 mL, what will the final temperature be?

QveST [7]

So to solve this you need to know Charles’s law which is: V1/T1=V2/T2. Where T1 and V1 is the initial volume and Temperature and V2 and T2 is the temperature and volume afterwards. So first plug in the numbers you are given. V1= 1.55L T1= 32C° V2= 755mL T2=?. Since your volumes are two different units you change 755mL to be in L so that would be 0.755 L. And since your temp isn’t in Kelvin you do 273+32= 305K°. You then would rearrange your equation to solve for T2 which is V2T1/V1. Then you plug in your numbers (0.755L)(305K)/1.55L. Then you solve and would be 148.5645161 —> 1.49 x 10^2 K

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2 years ago

2. Why does the CDC recommend hand sanitizers with at least 60% alcohol?! I

choli [55]

Answer:

Here's it:

Explanation:

Germs are everywhere! They can get onto hands and items we touch during daily activities and make us sick. Cleaning hands at key times with soap and water or hand sanitizer that contains at least 60% alcohol is one of the most important steps you can take to avoid getting sick and spreading germs to those around you.

There are important differences between washing hands with soap and water and using hand sanitizer. Soap and water work to remove all types of germs from hands, while sanitizer acts by killing certain germs on the skin. Although alcohol-based hand sanitizers can quickly reduce the number of germs in many situations, they should be used in the right situations.

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2 years ago

Which is associated with a fission reaction? *

podryga [215]

Answer: Radioactive waste

Explanation:

The nuclear fission reaction consists of heavy atomic particles or heavy nucleus, like plutonium and uranium and in radioactive heavy metals. In the fission reaction the nucleus get split into equal masses of particles. This process is associated with release of large amount of energy. The fission of radioactive waste can cause deadly mutations in living beings.

6 0

3 years ago

Effective nuclear charge, Zeff, is defined as:

Alborosie

Answer:

The effective nuclear charge for a valence electron in oxygen atom: $Z_{eff} = 4.55$

Explanation:

Effective nuclear charge $[Z_{eff}]$ is the net nuclear charge experienced by the electron in a given atom. It is always less than the actual charge of the nucleus [Z], due to shielding by electrons in the inner shells.

It is equal to the difference between the actual nuclear charge or the atomic number (Z) and the shielding constant (s).

$\Rightarrow Z_{eff} = Z - s$

For an oxygen atom-

Electron configuration: (1s²) (2s² 2p⁴)

The atomic number (actual nuclear charge): Z = 8

The shielding constant (s) for a valence electron can be calculated by using the Slater's rules:

⇒ s = 5 × 0.35 + 2 × 0.85 = 1.75 + 1.7 = 3.45

Therefore, the effective nuclear charge for a valence electron in oxygen atom is:

$Z_{eff} = Z - s = 8 - 3.45 = 4.55$

Therefore, the effective nuclear charge for a valence electron in oxygen atom: $Z_{eff} = 4.55$

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2 years ago