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2 years ago

Is caffeine optically active

1 answer:

7 0

Caffeine is not optically active because it is a planar heterocycle. When you say optically active, it means that compounds have molecules which are chiral. Chirality is the property of molecules as a result of its structure. And when you say planar heterocycle, molecules are flat and the ring should contain atoms located in a similar plane.

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Determine the theoretical yield of H2S (in moles) if 4.0 molAl2S3 and 4.0 mol H2O are reacted according to the followingbalanced

mamaluj [8]

Answer:

The theoretical yield of the hydrogen sulfide is 68.0 grams.

Explanation:

$Al_2S_3(s)+6H_2O(l)\rightarrow 2Al(OH)_3(s)+3H_2S(g)$

Moles of aluminum sulfide = 4.0 mol

Moles of water = 4.0 mol

According to reaction, 6 moles of water reacts with 1 mole of aluminum sulfide,then 4 moles of water will react with :

$\frac{1}{6}\times 4 mol=1.5 mol$ of aluminum sulfide

1.5 moles aluminum sulfide < 4 moles aluminum sulfide

This means that water is present in limiting amount and aluminum sulfide is in excess amount.So, amount of hydrogen sulfide will depend upon moles of water.

According to reaction, 6 moles of water gives with 3 mole of hydrogen sulfide,then 4 moles of water will give :

$\frac{3}{6}\times 4 mol=2.0 mol$ of hydrogen sulfide

Mass of hydrogen sulfide:

2.0 mol × 34 g/mol = 68.0 g

The theoretical yield of the hydrogen sulfide is 68.0 grams.

7 0

1 year ago

The compound Xe(CF3)2 decomposes in a first-order reaction to elemental Xe with a half-life of 30.0 min. If you place 4.5 mg of

GenaCL600 [577]

Answer : The time passed by the sample is, $1.2\times 10^2\text{ min}$

Explanation :

Half-life = 30.0 min

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{30.0\text{ min}}$

$k=0.0231\text{ min}^{-1}$

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $0.0231\text{ min}^{-1}$

t = time passed by the sample = ?

a = initial amount of the reactant = 4.5 mg

a - x = amount left after decay process =0.25 mg

Now put all the given values in above equation, we get

$t=\frac{2.303}{0.0231}\log\frac{4.5}{0.25}$

$t=125.15\text{ min}=1.2\times 10^2\text{ min}$

Therefore, the time passed by the sample is, $1.2\times 10^2\text{ min}$

7 0

2 years ago

Consider a culture medium on which only gram-positive organisms such as Staphylococcus aureus colonies can grow due to an elevat

Olin [163]

<h2>Selective & Differential Medium</h2>

Explanation:

Selective media allow specific types of organisms to develop, and inhibit the development of different living beings. The selectivity is cultivated in a few ways.For model, living beings that can use a given sugar are handily screened by making that sugar the main carbon source in the medium. On the other hand,selective hindrance of certain sorts of microorganisms can be accomplished by adding dyes, anti-infection agents, salts or explicit inhibitors which influence the digestion or enzyme systems of the living beings
Differential media are utilized to separate firmly related life forms or groups of living beings. owing to the pre of specific colors or synthetic compounds in the media, the creatures will deliver trademark changes or development designs that are utilized for ID or separation. An assortment of particular and differential media are utilized in clinical, demonstrative and water contamination research facilities, and in food and dairy laboratories
Selective media because elevated NaCI level is designed to help grow selective bacteria.differential media because the fermented sugar gives off a yellow halo which allows for differentiate between bacteria

4 0

2 years ago

You work for a cutlery manufacturer who wants to electrolytically precipitate 0.500 g of silver onto each piece of a batch of 25

ICE Princess25 [194]

Answer:

373.1 mL of AgCN (aq) must be poured into your electrolysis vat to ensure you have sufficient Ag to plate all of the forks.

Explanation:

Mass of silver to be precipitated on ecah spoon = 0.500 g

Number of silver spoons = 250

Total mass of silver = 250 × 0.500 g = 125 g

$Moles (n)=Molarity(M)\times Volume (L)$

Moles of AgCN = n = $\frac{125 g}{134 g/mol}=0.9328 mol$

Volume of AgCN solution =V

Molarity of the AgCN = 2.50 M

$V=\frac{0.9328 mol}{2.50 M}=0.3731 L=373.1 mL$

(1 L = 1000 mL)

373.1 mL of AgCN (aq) must be poured into your electrolysis vat to ensure you have sufficient Ag to plate all of the forks.

6 0

2 years ago

A student pours exactly 26.9 mL of HCl acid of unknown molarity into a beaker. The student then adds 2 drops of the indicator an

Assoli18 [71]

a.
Acids react with bases and give salt and water and the products.

Hence, HCl reacts with NaOH and gives NaCl salt and H₂O as the products. The reaction is,
HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

To balance the reaction equation, both sides hould have same number of elements.

Left hand side, Right hand side,
H atoms = 2   H atoms = 2
Cl atoms = 1   Cl atoms = 1
Na atoms = 1   Na atoms = 1
O atoms = 1   O atoms = 1

Hence, the reaction equation is already balanced.

b.
Molarity (M)= moles of solute (mol) / Volume of the solution (L)

HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

Molarity of NaOH = <span>0.13 M
</span>Volume of NaOH added = <span>43.7 mL
Hence, moles of NaOH added = 0.13 M x 43.7 x 10</span>⁻³ L
= 5.681 x 10⁻³ mol

Stoichiometric ratio between NaOH and HCl is 1 : 1

Hence, moles of HCl = moles of NaOH
= 5.681 x 10⁻³ mol

5.681 x 10⁻³ mol of HCl was in <span>26.9 mL.

Hence, molarity of HCl = </span>5.681 x 10⁻³ mol / 26.9 x 10⁻³ L
= 0.21 M

6 0

2 years ago