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3 years ago

Using water, how could you distinguish between the white solids NaCl and BaCO3?

1 answer:

5 0

Start with 0.5 g of each - place each in a separate 20 ml beaker containing 10 cc water. Swirl each beaker to dissolve the solids - The KCl will dissolve completely - the lead salt will not.

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Ibuprofen is a drug used to manage mild pain, fever, and inflammation. It is a chiral drug, and only the S enantiomer, whose spe

madam [21]

Answer:

Specific Rotation = 105º

S% in mixture = 92%

Explanation:

Specific rotation in organic compounds varies linearly, then the enantiomeric excess can be express as:

$e.e. = \frac{\alpha }{\alpha pure}$

Where alpha is the specific rotation of the mixture and alpha pure is the specific rotation of the excess enantiomer.

Then, knowing that the S enantiomer is in excess you can calculate the specific rotation of that mixture:

$84=\frac{\alpha }{125.0}*100$

$\alpha =105 Degrees$

For calculating the percentage of S you should remember that the enantiometric excess is the percentage of excess of a certain enantiomer, for example in this case:

$84 = S-R$

Since S is in Excess

Also, it is true:

$100=S+R$

Then you can solve the system of linear equations, finding:

$8=R\\92=S$

Hope it helps!

4 0

3 years ago

"Calculate the pH during the titration of 30.00 mL of 0.1000 M C3H7COOH(aq) with 0.1000 M LiOH(aq) after 29.9 mL of the base hav

Ivanshal [37]

Answer:

pH = 7.29

Explanation:

<em>Ka of butanoic acid is 1.54x10⁻⁵</em>

To obtain the pH of the solution you must use H-H equation for butanoic acid:

pH = pKa + log₁₀ [C₃H₇COO⁻] / [C₃H₇COOH]

Where pKa is defined as -log Ka = 4.81

Now, you need to find [C₃H₇COO⁻] and [C₃H₇COOH] concentrations (Also, you can find moles of each substance and replace them in the equation.

Butanoic acid reacts with LiOH, producing C₃H₇COO⁻, thus:

C₃H₇COOH + LiOH → C₃H₇COO⁻ + H₂O + Li⁺

Moles of both reactants, C₃H₇COOH and LiOH are:

C₃H₇COOH = 0.0300L ₓ (0.1000mol / L) = 0.003000moles of C₃H₇COOH

LiOH = 0.0299L ₓ (0.1000mol / L) = 0.00299 moles of LiOH.

That means moles of C₃H₇COO⁻ produced are <em>0.00299 moles</em>.

And moles of C₃H₇COOH that remains in solution are:

0.00300 - 0.00299 = <em>0.00001 moles of C₃H₇COOH</em>

Replacing in H-H equation:

pH = pKa + log₁₀ [C₃H₇COO⁻] / [C₃H₇COOH]

pH = 4.81 + log₁₀ [0.00299moles] / [0.00001moles]

7 0

4 years ago

A dehydration reaction starting with 3.8 g cyclohexanol produces 2.6 g cyclohexene. Calculate the theoretical yield for this rea

diamong [38]

Answer:

Theoretical yield of C6H10 = 3.2 g.

Explanation:

Defining Theoretical yield as the quantity of product obtained from the complete conversion of the limiting reactant in a chemical reaction. It can be expressed as grams or moles.

Equation of the reaction

C6H11OH --> C6H10 + H2O

Moles of C6H11OH:

Molar mass of C6H110H = (12*6) + (1*12) + 16

= 100 g/mol

Mass of C6H10 = 3.8 g

number of moles = mass/molar mass

=3.8/100

= 0.038 mol.

Using stoichoimetry, 1 moles of C6H110H was dehydrated to form 1 mole of C6H10 and 1 mole of water.

Therefore, 0.038 moles of C6H10 was produced.

Mass of C6H10 = molar mass * number of moles

Molar mass of C6H10 = (12*6) + (1*10)

= 82 g/mol.

Mass = 82 * 0.038

= 3.116 g of C6H10.

Theoretical yield of C6H10 = 3.2 g

4 0

4 years ago

Which phrase best describes a machine?

elena55 [62]

I believe the best answer is D.
All answers contribute to a machine, if there is an all above choice, chose that.

7 0

3 years ago

Read 2 more answers

What is the most abundant gas in our atmosphere?

Doss [256]

Nitrogen <---- Itś at 73% of Earths atmosphere.

4 0

3 years ago

Read 2 more answers