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3 years ago

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For the reaction show below determine the rate law. H2SO3(aq) + 6I-(aq) + 4H+(aq) → S(s) + 2I3- + 3H2O (l) In the presence of a

little starch, this solution turns from colorless to blue when I3- is formed. The following data were obtained: [H2SO3] [H+] [I-] Initial Rate (mol/L s) 1.0 x 10-2 2.0 x 10-1 2.0 x 10-1 1.66 x 10-7 3.0 x 10-2 2.0 x 10-1 2.0 x 10-1 4.98 x 10-7 1.0 x 10-2 1.0 x 10-1 2.0 x 10-1 8.30 x 10-8 1.0 x 10-2 2.0 x 10-1 4.0 x 10-1 13.2 x 10-7 Calculate the rate law for this reaction: rate = k [H2SO3] [H+] [I-

1 answer:

alekssr [168]3 years ago

7 0

Answer:

Please see the attached picture for the complete answer.

Explanation:

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The unit cell for cr2o3 has hexagonal symmetry with lattice parameters a = 0.4961 nm and c = 1.360 nm. If the density of this ma

IRINA_888 [86]

To calculate the packing factor, first calculate the area and volume of unit cell.

Area is calculated as:

$A=6R^{2}\sqrt{3}$

Here, R is radius and is related to a as follows:

$R=\frac{a}{2}$

Putting the value in expression for area,

$A=6(\frac{a}{2})^{2}\sqrt{3}=1.5a^{2}\sqrt{3}$

The value of a is 0.4961 nm

Since, $1 nm=10^{-7}cm$

Thus, $0.4961 nm=4.961\times 10^{-8} cm$

Putting the value,

$Area=1.5(4.961\times 10^{-8}cm)^{2}\sqrt{3}=6.39\times 10^{-15}cm^{2}$

Now, volume can be calculated as follows:

$V=Area\times c$

The value of c is 1.360 nm or $1.360\times 10^{-7} cm$

Putting the value,

$V=(6.39\times 10^{-15}cm^{2})\times (1.360\times 10^{-7} cm)=8.7\times 10^{-22}cm^{3}$

now, number of atom in unit cell can be calculated by using the following formula:

$n=\frac{\rho N_{A}V_{c}}{A}$

Here, A is atomic mass of $Cr_{2}O_{3}$ is 151.99 g/mol.

Putting all the values,

$n=\frac{(5.22 g/cm^{3})(6.023\times 10^{23} mol^{-1})(8.7\times 10^{-22}cm^{3})}{(151.99 g/mol)}\approx 18$

Thus, there will be 18 $Cr_{2}O_{3}$ units in 1 unit cell.

Since, there are 2 Cr atoms and 3 oxygen atoms thus, units of chromium and oxygen will be 2×18=36 and 3×18=54 respectively.

The atomic radii of $Cr^{3+}$ and $O^{2-}$ is 62 pm and 140 pm respectively.

Converting them into cm:

$1 pm=10^{-10}cm$

Thus,

$r_{Cr^{3+}}=6.2\times 10^{-9}cm$

and,

$r_{O^{2-}}=1.4\times 10^{-8}cm$

Volume of sphere will be sum of volume of total number of cations and anions thus,

$V_{S}=V_{Cr^{3+}}+V_{O^{2-}}$

Since, volume of sphere is $V=\frac{4}{3}\pi r^{3}$ ,

$V_{S}=36\left ( \frac{4}{3}\pi (r_{Cr^{3+})^{3}} \right )+54\left ( \frac{4}{3}\pi (r_{O^{2-})^{3}} \right )$

Putting the values,

$V_{S}=36\left ( \frac{4}{3}(3.14) (6.2\times 10^{-9} cm)^{3}} \right )+54\left ( \frac{4}{3}(3.14) (1.4\times 10^{-8} cm)^{3}} \right )=6.6\times 10^{-22}\times 10^{-8}cm^{3}$

The atomic packing factor is ratio of volume of sphere and volume of crystal, thus,

$packing factor=\frac{V_{S}}{V_{C}}=\frac{6.6\times 10^{-22}cm^{3}}{8.7\times 10^{-22}cm^{3}}=0.758$

Thus, atomic packing factor is 0.758.

6 0

3 years ago

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• We obtained the above 10.00-mL solution by diluting a stock solution using a 1.00-mL aliquot and placing it into a 25.00-mL vo

garik1379 [7]

Answer:

a) The relationship at equivalence is that 1 mole of phosphoric acid will need three moles of sodium hydroxide.

b) 0.0035 mole

c) 0.166 M

Explanation:

Phosphoric acid is tripotic because it has 3 acidic hydrogen atom surrounding it.

The equation of the reaction is expressed as:

$H_3PO_4 \ + \ 3NaOH -----> Na_3 PO_4 \ + \ 3H_2O$

1 mole 3 mole

The relationship at equivalence is that 1 mole of phosphoric acid will need three moles of sodium hydroxide.

b) if 10.00 mL of a phosphoric acid solution required the addition of 17.50 mL of a 0.200 M NaOH(aq) to reach the endpoint; Then the molarity of the solution is calculated as follows

$H_3PO_4 \ + \ 3NaOH -----> Na_3 PO_4 \ + \ 3H_2O$

10 ml 17.50 ml

(x) M 0.200 M

Molarity = $\frac{0.2*17.5}{1000}$

= 0.0035 mole

c) What was the molar concentration of phosphoric acid in the original stock solution?

By stoichiometry, converting moles of NaOH to H₃PO₄; we have

= $0.0035 \ mole \ of NaOH* \frac{1 mole of H_3PO_4}{3 \ mole \ of \ NaOH}$

= 0.00166 mole of H₃PO₄

Using the molarity equation to determine the molar concentration of phosphoric acid in the original stock solution; we have:

Molar Concentration = $\frac{mole \ \ of \ soulte }{ Volume \ of \ solution }$

Molar Concentration = $\frac{0.00166 \ mole \ of \ H_3PO_4 }{10}*1000$

Molar Concentration = 0.166 M

∴ the molar concentration of phosphoric acid in the original stock solution = 0.166 M

6 0

3 years ago

Try to rationalize the sign of ΔS∘rxn in each case.

bonufazy [111]

Answer:

a) decrease, gas

b) increase, gas

c) liquid

d) increase, solid

Explanation:

Entropy refers to the degree of disorderliness of a system. If the number of moles of gas increases from left to right in a reaction, the entropy of the system increases positively.

Similarly, when the number of liquid molecules remain constant, there could only be a very little increase in entropy.

However, solids have the least entropy and the entropy of a system decreases when a system yields solid products.

6 0

3 years ago

Which compound is produced when HCl(aq) is neutralized by Ca(OH)2(aq)?

kiruha [24]

<u>Answer:</u> The correct answer is Option 1.

<u>Explanation:</u>

Neutralization reaction is defined as the reaction in which acid reacts with a base to produce a salt along with water.

Here, HCl is an acid and $Ca(OH)_2$ is a base. When these two compounds react, the salt obtained is calcium chloride.

The equation for the above reaction is given by:

$2HCl(aq.)+Ca(OH)_2(aq.)\rightarrow CaCl_2(s)+2H_2O(l)$

Hence, the correct answer is Option 1.

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3 years ago

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An atom of selenium (Se) forms a monatomic ion. Which of the following ions does it most likely form? Se2+ Se2 Se6+ Se6 *Not exp

Nikolay [14]

<span>I didn't know Selenium was considered organic? :P atoms form ions that mimic the electronic structure of noble gases. so add or subtract electrons from the atom to achieve the configuration of a noble gas.</span>

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3 years ago

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