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3 years ago

How do I calculate the standard enthalpy change for the following reaction at 25 °C ?

1 answer:

4 0

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g)

Using the standard enthalpies of formation given in the source below:

(−601.24 kJ) + (2 x −92.30 kJ) − (−641.8 kJ) − (−285.8 kJ) = +141.76 kJ
So:

MgCl2(s) + H2O(l) → MgO(s) + 2 HCl(g), ΔH = +141.76 kJ

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What do elements in the same group in the periodic table have in common

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Answer:

The elements in each group have the same number of electrons in the outer orbital. Those outer electrons are also called valence electrons.

Explanation:

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2 years ago

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2 years ago

S-2-iodooctane lost his opticaly activity in soln on tratment wwithNaI. Explain

IceJOKER [234]

Answer:

Repeated SN2 reactions occur leading to the formation of a racemic mixture

Explanation:

S-2-iodooctane is a chiral alkyl halide with an asymmetric carbon atom. The presence of an asymmetric carbon atom implies that it can rotate plane polarized light and thus lead to optical isomerism. The two configurations of the compound are R/S according to the Cahn-Prelong-Ingold system.

However, when S-2-iodooctane is treated with sodium iodide in acetone, repeated SN2 reactions occur since the iodide ion is both a good nucleophile and a good leaving group. Hence a racemic modification is formed in the system with time hence we end up with (±)- Iodooctane.

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3 years ago

Explain how to convert a mass of compound A to a mass of compound D in words with no equations using the following reaction 2A +

leonid [27]

Answer:

Explanation:

The given reaction equation is:

2A + 4B → C + 3D

We know the mass of compound A in the reaction above. We are to find the mass of compound D.

We simply work from the known mass to calculate the mass of the unkown compound D

Using the mole concept, we can find the unknown mass.

Procedures

We first find the molar mass of the compound A from the atomic units of the constituent elements.
We then use the molar mass of A to calculate its number of moles using the expression below:

Number of moles of A = $\frac{mass of A}{molar mass of A}$

Using the known number of moles of A, we can work out the number of moles of D.

From the balanced equation of the reaction, it is shown that:

2 moles of compound A was used up to produced 3 moles of D

Then $\frac{3}{2}$ x number of moles of A would give the number of moles of D

Now that we know the number of moles of D, we can find its mass using the expression below:

Mass of D = number of moles of D x molar mass of D

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2 years ago

Helium has a density of 1.79 x 10-4 g/mL at standard temperature and pressure. A balloon has a volume of 6.3 liters. Calculate t

sukhopar [10]

To find the mass you divide multiply volume and density..

Density = 1.79 x 10^-4 Volume = 6.3

(1.79 x 10^-4 )(6.3) = <span>1.1 x 10^-3 g
</span>

7 0

2 years ago

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