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2 years ago

If 91.0 g of oxalic acid and 79.0 g of methanol react to form 89.0 g of dimethyl oxalate, what is the percent yield?

1 answer:

6 0

Thank you for posting your question here at brainly.

H2C2O4 + 2 CH3OH → (CH3)2(COO)2 + 2 H2O

(91.0 g H2C2O4) / (90.0349 g H2C2O4/mol) = 1.0107 mol H2C2O4 
(79.0 g CH3OH) / (32.0419 g CH3OH/mol) = 2.4655 mol CH3OH 

(1.0107 moles of H2C2O4 would react completely with 1.0107 x (2/1) = 2.0214 moles of CH3OH, but there is more CH3OH present than that, so CH3OH is in excess and H2C2O4 is the limiting reactant. 

(1.0107 mol H2C2O4) x (1 mol (CH3)2(COO)2 / 1 mol H2C2O4) x (118.0880 g (CH3)2(COO)2/mol) = 
119.35 g (CH3)2(COO)2 in theory 

(89.0 g) / (119.35 g) = 0.746 = 74.6% yield

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What is the pH of a 0.050 M triethylamine, (C2H5)3N, solution? Kb for triethylamine is 5.3 ´ 10-4. Question options: 1) 11.69 2)

blsea [12.9K]

the pH of a 0.050 M triethylamine, is 11.70

For triehtylamine, $(C_{2}H_{5})_{3}N$ , the reaction will be
$(C_{2}H_{5})_{3}N + H_{2}O ---\ \textgreater \ ( C_{2}H_{5})_{3}NH^{+} + OH^{-}$

and we know, pH = -log[H+] and pOH = -log[OH-]

Also, pOH + pH = 14

Now, the Kb value = 5.3 x 10^-4

And $kb = \frac{( [( C_{2}H_{5})_{3}NH^{+} ]* OH^{-} )}{[( C_{2}H_{5})_{3}N]}$

thus, [OH-] =(5.3 ^ 10-4) ^2 / 0.050

=0.00516 M

Thus, pOH = 2.30
pH = 14 - pOH = 11.7

6 0

2 years ago

Acetonitrile (CH3CN) is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a 1

erastovalidia [21]

Answer:

a. [LiBr] = 2.70 m

b. Xm for LiBr = 0.1

c. 81% by mass CH₃CN

Explanation:

Solvent → Acetonitrile (CH₃CN)

Solute → LiBr, lithium bromide

We convert the moles of solute to mass → 1.80 mol . 86.84 g/1 mol = 156.3 g

This mass of solute is contained in 1L of solution

1 L = 1000 mL → 1mL = 1cm³

We determine solution mass by density

Solution density = Solution mass / Solution volume

Solution density . Solution volume = solution mass

0.824 g/cm³ . 1000 cm³ = 824 g

Mass of solution = 824 g (solvent + solute)

Mass of solute = 156.3 g

Mass of solvent = 824 g - 156.3 g = 667.7 g

Molality → Moles of solute in 1kg of solvent

We convert the mass of solvent from g to kg → 667.7 g . 1kg /1000g = 0.667 kg

Mol/kg → 1.80 mol / 0.667 kg = 2.70 m → molality

Mole fraction → Mole of solute / Total moles (moles solute + moles solvent)

Moles of solvent → 667.7 g . 1mol/ 41g = 16.3 moles

Total moles = 16.3 + 1.8 = 18.1

Mole fraction Li Br → 1.80 moles / 18.1 moles = 0.1

Mass percentage → (Mass of solvent, in this case / Total mass) . 100

We were asked for the acetonitrile → (667.7 g / 824 g) . 100 = 81%

3 0

2 years ago

Identify the precipitate(s) formed when solutions of na2so4(aq), ba(no3)2(aq), and nh4clo4(aq) are mixed.

Lostsunrise [7]

Answer : BaS $O_{4}$ will be the precipitate which will be formed.

Explanation : When all the three solutions namely; $NaSO_{4} + Ba(NO_{3})_{2} + NH_{4} ClO_{4}$ are mixed together a white precipitate of BaS $O_{4}$ is formed as a product in the solution along with the soluble by product of Ammonium nitrate which is $NH_{4} NO_{3}$

7 0

2 years ago

Oxide formation by heating element in oxygen atmosphere are best classified as which type of reaction?a. Synthesis b. Double dis

Bond [772]

Answer: a. Synthesis

Explanation:

a. Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.

Example: $Mg+O_2\rightarrow 2MgO$

Thus magnesium in its elemental form is combining with oxygen to form magnesium oxide.

b. Double displacement reaction is one in which exchange of ions take place.

Example: $2NaOH(aq)+(NH_4)_2SO_4(aq)\rightarrow 2NH_4OH(aq)+Na_2SO_4(aq)$

c. Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.

Example: $Li_2CO_3\rightarrow Li_2O+CO_2$

5 0

2 years ago

When the Modern Museum of Art separated its consumers by whether they were culture-oriented or outdoor-oriented for its new exhi

madam [21]

Answer:

A. psychographic lifestyle segmentation

Explanation:

Psychographic lifestyle segmentation -

It refers to the distribution or classification method , where the consumers of a particular goods and services are classified into particular groups , depending on the psychological characteristics of the consumers , is referred to as psychographic lifestyle segmentation .

The segmentation take care of the consumers celief , priority , va;ues , decision - making process , lifestyle .

The method enables to market the goods and services in a better manner , nd increases the profit of the company .

Hence , from the given scenario of the question ,

The correct option is A. psychographic lifestyle segmentation .

8 0

2 years ago