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Allushta [10]
3 years ago
9

Please help due today

Chemistry
1 answer:
Olegator [25]3 years ago
4 0
1,1,2 & single replacement reaction
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Which of the following pairs are isotpes?
grin007 [14]
The answer is B because isotopes have the same number of protons and neutrons.
5 0
3 years ago
What volume of 0.307 m naoh must be added to 200.0ml of 0.425m acetic acid (ka = 1.75 x 10-5 ) to produce a buffer of ph = 4.250
Blababa [14]

The buffer solution target has a pH value smaller than that of pKw (i.e., pH < 7.) The solution is therefore acidic. It contains significantly more protons \text{H}^{+} than hydroxide ions \text{OH}^{-}. The equilibrium equation shall thus contain protons rather than a combination of water and hydroxide ions as the reacting species.

Assuming that x \; \text{L} of the 0.307 \text{mol} \cdot \text{dm}^{-3} sodium hydroxide solution was added to the acetic acid. Based on previous reasoning, x is sufficiently small that acetic acid was in excess, and no hydroxide ion has yet been produced in the solution. The solution would thus contain 0.2000 \times 0.425 - 0.307 \; x = 0.085 - 0.307 \; x moles of acetic acid and 0.307 \; x moles of acetate ions.

Let \text{HAc} denotes an acetic acid molecule and \text{Ac}^{-} denotes an acetate ion. The RICE table below resembles the hydrolysis equilibrium going on within the buffer solution.

\begin{array}{lccccc}\text{R} & \text{HAc} & \leftrightharpoons & \text{H}^{+} & + & \text{Ac}^{-}\\\text{I} & 0.085 - 0.307 \; x& & 0 & & 0.307 \; x\\\end{array}

The buffer shall have a pH of 4.250, meaning that it shall have an equilibrium proton concentration of 10^{4.250}\; \text{mol}\cdot \text{dm}^{-3}. There were no proton in the buffer solution before the hydrolysis of acetic acid. Therefore the table shall have an increase of 10^{-4.250}\;\text{mol}\cdot \text{dm}^{-3} in proton concentration in the third row. Atoms conserve. Thus the concentration increase of protons by 10^{-4.250}\;\text{mol}\cdot \text{dm}^{-3} would correspond to a decrease in acetic acid concentration and an increase in acetate ion concentration by the same amount. That is:

\begin{array}{lcccccc}\text{R} & \text{HAc} & \leftrightharpoons & \text{H}^{+} & + & \text{Ac}^{-}\\\text{I} & 0.085 - 0.307 \; x& & 0 & & 0.307 \; x\\\text{C} & - 10^{-4.250} & & +10^{-4.250} & & +10^{-4.250} \\\text{E} & 0.085 - 10^{-4.250} - 0.307 \; x& & 10^{-4.250} & & 10^{-4.250} + 0.307 \; x\end{array}

By definition:

\text{K}_{a} = [\text{H}^{+}] \cdot [\text{Ac}^{-}] / [\text{HAc}]\\\phantom{\text{K}_{a}} = 10^{-4.250} \times (10^{-4.250} + 0.307 \; x) / (0.085 - 10^{-4.250} - 0.307 \; x)

The question states that

\text{K}_{a} = 1.75 \times 10^{-5}

such that

10^{-4.250} \times (10^{-4.250} + 0.307 \; x) / (0.085 - 10^{-4.250} - 0.307 \; x) = 1.75 \times 10^{-5}\\6.16 \times 10^{-5} \; x = 1.48 \times 10^{-6}\\x = 0.0241

Thus it takes 0.0241 \; \text{L} of sodium hydroxide to produce this buffer solution.

6 0
3 years ago
How many molecules are in 189.5 grams of no2?
xz_007 [3.2K]
<span>NO2 weighs 46.005 grams per mol. There are 6.02x10^23 molecules in a mol. In the given sample of 189.5 grams, there are 4.12 mols. This means that there are 2.48x10^24 molecules of NO2 in the given sample.</span>
5 0
3 years ago
. Guillermo was finding it difficult to walk up the steps to his family’s apartment. His doctor thinks that his cells might not
morpeh [17]

Answer:

Because oxygen is the combustion  fuel and glucose  is the substrate needed for synthesis of energy as ATPs during cellular respiration.Therefore Guillermo lacks enough energy as ATPs in her  body cells, especially skeletal muscles cells to complete the task of ascending the s steps.

For all the mitochondrial in cells(sites of energy production)   to receive needed glucose,and other metabolites needed for  energy synthesis; an efficient transport system is needed, so that  these materials   are available  immediately, in required amount. This system is called circulatory system.

And for the the supply of combustion fuel (oxygen) needed for the completion of the ATP synthesis mechanisms;  respiratory systems which  convey oxygen from the external environments to the circulatory system through breathing mechanisms, for distribution is needed.

Thus the  doctor needs to test both the circulatory and respiratory systems.

Explanation:

4 0
2 years ago
Cans of regular soda have volumes with a mean of 14.5 oz and a standard deviation of 0.18 oz. What is the maximum "usual" value
tangare [24]

Answer:

14.68 oz

Explanation:

The mean volume is the average volume of all the regular soda cans put together; 14.5 oz. The standard deviation 0.18 oz is the maximum deviation from the mean. It can be 14.5-0.18= 14.32 oz which is the usual minimum or 14.5 + 0.18=14.68 oz which is the usual maximum

4 0
3 years ago
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