The balanced chemical reaction is written as:
<span>4C(s) + S8(s) → 4CS2(l)
We are given the amount of carbon and sulfur to be used in the reaction. We need to determine first the limiting reactant to be able to solve this correctly.
</span>7.70 g C ( 1 mol / 12.01 g) =0.64 mol C
19.7 g S8 ( 1 mol / 256.48 g) = 0.08 mol S8
The limiting reactant would be S8. We use this amount to calculate.
0.08 mol S8 ( 4 mol CS2 / 1 mol S8 ) ( 256.48 g / 1 mol ) = 78.8 g CS2
A and C are incorrect because they are not complete transfer of valence electrons. Ionic bonds best to form a neutral molecule
Answer: 4.18925 kJ heat is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.
Explanation:
Temperature of Solid 
Melting temperature of Solid 
Temperature of liquid 
Specific heats of solid ethanol = 0.97 J/gK
Specific heats of liquid ethanol = 2.3 J/gK
Heat required to melt the the 25 g solid 
at 159 K
= 159 K - 138 K = 21 K
Heat required to melt and raise the temperature of upto 223 K
= 223 K - 159 K = 64 K
Total heat to convert solid ethanol to liquid ethanol at given temperature :
(1kJ=1000J)
Hence, 4.18925 kJ of heat will be required to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.
We can explain this in a molecular level. We know that the difference between a gas and a liquid of the same composition is how fast their molecules are moving. So given a gas, their molecules are farther and faster when moving, but when they are cooled their bulk kinetic energy decreases. In other words their molecules start to move closer and move slower until it behaves more like a liquid molecule. This is the time when gases condense.
We can skip option B and D because NaCl is salt and H₂SO₄ is a strong acid.
Neutralization reactions are those reactions in which acid and base react to form salt and water.
As water being amphoteric in nature can react with HCl as follow,
HCl + H₂O ⇆ H₃O⁺ + OH⁻
In this case no salt is formed, so we can skip this option.
Ammonia being a weak base can abstract proton from HCl as follow,
HCl + NH₃ → NH₄Cl
Ammonium Chloride is a salt. So, among all four options, Option-C is the correct answer.
