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3 years ago

Using the following balanced equation:

Chemistry

1 answer:

marshall27 [118]3 years ago

6 0

Answer:2Al(s) + 3H2SO4(aq) ==> Al2(SO4)3(aq) + 3H2(g) ... balanced equation

Using the stoichiometry of the balanced equation (2 mol Al : 3 mol H2SO4) and dimensional analysis, we can find the mass of Al needed to react with 26.5 ml of 0.542 M H2SO4.

Explanation:

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What type of igneous rock has large crystals

VARVARA [1.3K]

Extrusive rock because it takes longer to cool, making the crystal size larger

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3 years ago

Adenosine triphosphate, or ATP, is primarily used as _______ in living organisms.

Stolb23 [73]

It is primarily used as a way to supply energy to other cells

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3 years ago

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What is the pH of a mixture of equal volumes of 0.6 mM Lactic acid and 0.4 mM NaOH?

tino4ka555 [31]

Answer:

The pH of the mixture is approximately 4.2.

There's no equilibrium calculation involved if HCl is used instead of lactic acid. The pH of that solution will be approximately 3.7.

Explanation:

<h3>Lactic Acid</h3>

Lactic acid is a monoprotic acid. In other words, each lactic acid molecule can be ionized to release only one proton. Therefore, lactic acid will react with NaOH at a 1-to-1 ratio. The result will be one unit of the anion of lactate ion.

Lactic acid is in excess. All NaOH will be consumed. Before any dissociation takes place, the solution will contain 0.2 mM of lactic acid and 0.4 mM of lactate ions.

Lactic acid is a weak acid. The following equilibrium will take place in the solution:

$\rm C_3H_6O_3 \leftrightharpoons {C_3H_5O_3}^{-} + H^{+}$ .

Let the increase in the concentration of protons in the solution be $x\rm \;M$ . Construct a RICE table:

$\begin{array}{c|ccccc}\rm \textbf{R}&\rm C_3H_6O_3 & \leftrightharpoons &\rm {C_3H_5O_3}^{-}& +& \rm H^{+}\\\textbf{I} & 0.2\times 10^{-3} && 0.4\times 10^{-3} \\\textbf{C} & -x & & +x & & +x\\\textbf{E} & 0.2\times 10^{-3} -x & & 0.4\times 10^{-3} + x & & x\end{array}$ .

The pKa value of lactic acid is 3.86. Therefore, $K_{\rm a} = 10^{-3.86}$ . By the definition of the acid dissociation constant $K_{\rm a}$ ,

$\begin{aligned} K_{\rm a} &= \frac{\rm [H^{+}][{C_3H_5O_3}^{-}]}{[\rm C_3H_6O_3]}\\& = \frac{x(0.4\times 10^{-3} +x)}{(0.6 \times 10^{-3} - x)}\end{aligned}$ .

Given that $K_{\rm a} = 10^{-3.86}$ , solve for $x$ :

$\displaystyle \frac{x(0.4\times 10^{-3} - x)}{0.2 \times 10^{-3}-x} = 10^{-3.86}$ .

There might be more than one solutions. However, the correct solution shall ensure that all concentrations are greater than zero. In this case,

$x \approx 5.7\times 10^{-5}$ .

By the definition of pH,

$\rm pH = -\log_{10}{[H^{+}]} = -\log_{10}{5.7\times 10^{-5}} \approx 4.2$ .

The Henderson-Hasselbalch equation will yield a similar result.

Similar to lactic acid, HCl is also monoprotic. The solution will contain 0.2 mM of HCl and 0.4 mM of NaCl before any ionization takes place.

Unlike lactic acid, all that 0.2 mM of HCl will ionize to produce protons and chloride ions. The final proton concentration in the solution will be 0.2 mM. As a result,

$\rm pH = - \log_{10}{[H^{+}]} = -\log_{10}{0.2\times 10^{-3}} \approx 3.6$ .

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4 years ago

When 3.2g of ammonium chloride is dissolved in 75g of water, the temperature of the solution decreases from 22.8 C to 20.1 C. Wh

ser-zykov [4K]

Dissolving NH4Cl in H2O is an endothermic solution process. You measure how much it cools the solution by the temperature of the H2O.
<span>q = mass H2O x specific heat H2O x (Tfinal-Tinitial) </span>
<span>The q you measure is for 3.2g/53.4g or q/0.0599 mol. You want to convert that to q/1 mol. </span>

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4 years ago

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Why is the absorbance versus concentration curve for a substance rarely straight for all concentrations?

nexus9112 [7]

In fact, it should be a straight line but the curve is rarely straight when the concentrations are either to high or to low.
This is due to the accuracy of the spectrometer. If concentration is too low, the amount of light transmitted is near 100% of the incident light and the electronic device can not measure it precisely. In an opposite way then the concentration is too high, the amount of light transmitted is too low and can not be measured accurately. However Beer-lambert law holds.

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4 years ago