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mrs_skeptik [129]
3 years ago
15

Which if the following is likely to be found in placer deposits

Chemistry
1 answer:
cestrela7 [59]3 years ago
3 0
The answer is A. Gold
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Draw the product that valine forms when it reacts with excess CH3CH2OH and HCl followed by a wash with aqueous base.
-BARSIC- [3]

Answer:

Product: ethyl L-valinate

Explanation:

If we want to understand what it is the molecule produced we have to an<u>alyze the reagents</u>. We have valine an <u>amino acid</u>, in this kind of compounds we have an <em>amine group</em> (NH_2) and a <em>carboxylic acid</em> group (COOH).  Additionally, we have an <u>alcohol </u>(CH_3CH_2OH) in the presence of HCl (a <u>strong acid</u>) in the first step, and a base (OH^-).

When we have an acid and an alcohol in a vessel we will have an <u>esterification reaction</u>. In other words, an ester is produced. As the <em>first step,</em> the oxygen in the C=O (in the carboxylic acid group) would be protonated. In the <em>second step</em>, the ethanol attacks the carbon in the C=O of the carboxylic acid group producing a new bond between the oxygen in the ethanol and the carbon in the carboxylic acid. In <em>step 3</em>, a proton is transferred to produce a better leaving group (H_2O). In <em>step 4</em>, a water molecule leaves the main structure to produce again the double bond C=O. <em>Finally</em>, a base (OH^-) removes the hydrogen from the C=O bond to produce ethyl L-valinate

See figure 1

I hope it helps!

7 0
3 years ago
How many atoms are in 13.97 liters of water vapor at STP
Arisa [49]
<span>Let's </span>assume that water vapor has ideal gas behavior. <span>
Then we can use ideal gas formula,
PV = nRT<span>

</span><span>Where, P is the pressure of the gas (Pa), V is the volume of the gas (m³), n is the number of moles of gas (mol), R is the universal gas constant ( 8.314 J mol</span></span>⁻¹ K⁻¹) and T is temperature in Kelvin.<span>
<span>
</span>P = 1 atm = 101325 Pa (standard pressure)
V = 13.97 L = 13.97 x 10</span>⁻³ m³<span>
n = ?
R = 8.314 J mol</span>⁻¹ K⁻¹<span>
T = 0 °C = 273 K (standard temperature)
<span>
By substitution,
</span>101325 Pa x 13.97x 10</span>⁻³ m³ = n x 8.314 J mol⁻¹ K⁻¹ x 273 K<span>
                                          n = 0.624 mol
<span>
Hence, the moles of water vapor at STP is 0.624 mol.

According to the </span></span>Avogadro's constant, 1 mole of substance has 6.022 × 10²³ particles.
<span>
Hence, number of atoms in water vapor = 0.624 mol x </span>6.022 × 10²³ mol⁻¹
<span>                                                                = 3.758 x 10</span>²³<span>

</span>
5 0
3 years ago
What happens to the composition of an atom to cause it to become positively or negatively charged?
uranmaximum [27]
It gains or loses electrons to become like the Noble gases having 8 valence electrons to become the most stable.
4 0
3 years ago
2Fe(OH)3 Fe2O3+3H2O how many grams of Fe2O3 are produced if 10.7 grams of Fe (OH)3 react in this way
sasho [114]

Answer: 7.98 grams of Fe_2O_3 are produced if 10.7 grams of Fe(OH)_3 are reacted.

Explanation:

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}      .....(1)  

Putting values in equation 1, we get:

\text{Moles of} Fe(OH)_3=\frac{10.7g}{106.87g/mol}=0.100mol  

The chemical equation for the reaction is

2Fe(OH)_3\rightarrow Fe_2O_3+3H_2O

By Stoichiometry of the reaction:

2 moles of Fe(OH)_3 produce = 1 mole of Fe_2O_3

So, 0.100 moles of Fe(OH)_3 produce= \frac{1}{2}\times 0.100=0.05mol of Fe_2O_3  

Mass of Fe_2O_3 =moles\times {\text{Molar Mass}}=0.05mol\times 159.69g/mol=7.98g  

Hence 7.98 grams of Fe_2O_3 are produced if 10.7 grams of Fe(OH)_3 are reacted.

3 0
2 years ago
The fossil record provides evidence of past life as well as clues to the past climate, environment, and abiotic factors in an ar
murzikaleks [220]
That is true because fossils can tell many things. 
5 0
3 years ago
Read 2 more answers
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