What does the subscript in chemicial formulas tell you?

State whether the sign of the entropy change expected for each of the following processes will be positive or negative, and expl

Strike441 [17]

Answer:

a) ΔS is negative

b) ΔS is positive

c) ΔS is positive

d) ΔS is negative

Explanation:

Entropy (S) is a thermodynamic parameter which measures the randomness or the disorder in a system. Greater the disorder more positive will be the value of entropy.

The extent of disorder increases as substances transition from the solid to the gaseous state. i.e.

S(solid) < S(liquid) < S(gas)

The entropy change for a given reaction is:

$\Delta S = S(products)-S(reactants)----(1)$

a) $PCl3(l) + Cl2(g) \rightarrow PCl5(s)$

Here the reactants are in the liquid and gas phase which have higher entropy than the product which is in the solid phase i.e. lower entropy.

Since S(product) < S(reactant), based on equation 1, ΔS will be negative.

b) $2HgO(s) \rightarrow 2Hg(l) + O2(g)$

Here the products are in the liquid and gas phase which have higher entropy than the reactant which is in the solid phase i.e. lower entropy.

Since S(product) > S(reactant), based on equation 1, ΔS will be positive.

c) $H2(g) \rightarrow 2H(g)$

Here the products and reactants are in the gas phase. However the number of moles of products is greater than the reactants

Since S(product) > S(reactant), based on equation 1, ΔS will be positive.

d) $U(s) + 3F2(g) \rightarrow UF6(s)$

Here one of the reactants is in the gas phase which corresponds to a more positive entropy compared to the product which is in the solid phase i.e. lower entropy.

Since S(product) < S(reactant), based on equation 1, ΔS will be negative.

8 0

3 years ago

Find the number of molecules equal to 1.46 molecules of CaCl2

stiv31 [10]

Answer:

8.7892x10^23

Explanation:

number of molecules equal number of moles times 6.02x10^23

6 0

3 years ago

Which of the following statements explains why atoms are always neutral in charge

laila [671]

Answer:

D. They have the same number of protons as electrons.

Explanation:

Protons are found in the nucleus of the atom and have a positive charge while electrons orbit around the nucleus and have a negative charge. Usually, in a neutral atom of an element, the number of protons is equal to the number of electrons. This is why the atom has no charge because the positive and negative charges cancel out. When an atom loses an electron its charge turns positive while when it gains an electron its charge turns negative.

6 0

1 year ago

Sodium is a larger atom than lithium. List three reasons why this is true.

just olya [345]

Answer:

It is present in third period that's why its valance electrons are present in 3rd energy level.

Its atomic number is greater than lithium when compared in group wise.

There are more electrons in sodium to shield the outer valance electron thus nuclear attraction becomes weak and size increase.

Explanation:

The size of sodium is greater than lithium because atomic number of sodium is 11 and lithium is 3. Both are present in first group but sodium is present down to the lithium. As we move from top to bottom in a group atomic size increases with addition of electrons. The nuclear effect become weaker on valance electrons and atomic size increase. Same time shielding effect is also produces which shield the outer electrons from the influence of nucleus. While in case of lithium less electrons are present to shield the valance electrons.

As we note the position of both elements along period. The sodium is present in third period while lithium is present in second period. So, in case of sodium third energy level is involved. That's why its size is greater than lithium.

8 0

3 years ago

Describe a procedure to separate a mixture of sugar, black pepper, and pebbles.

stiks02 [169]

Pass the mixture through a screen to allow the salt and pepper to pass through but traps the pebbles. Mix the salt and pepper with water to dissolve the salt and filter it to get the pepper.

8 0

3 years ago

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