C2H4 + HCL --> C2H5CL dH=-723 kj find dE if 98g c2h4 and 1095 g hcl is reacted at 300 K

To find the change in internal energy (ΔE) for the reaction of ethylene (C2H4) with hydrochloric acid (HCl) to form chloroethane (C2H5Cl), we can start by using the relationship between enthalpy change (ΔH) and internal energy change (ΔE). The equation we will use is:

ΔE = ΔH - ΔnRT

In this equation:

• ΔH is the change in enthalpy, which is given as -723 kJ.
• Δn is the change in the number of moles of gas during the reaction.
• R is the universal gas constant, approximately 8.314 J/(mol·K).
• T is the temperature in Kelvin, which is given as 300 K.

Step 1: Determine the balanced chemical equation

The balanced equation for the reaction is:

C2H4(g) + HCl(g) → C2H5Cl(l)

Step 2: Calculate the change in moles of gas (Δn)

In this reaction, we start with 2 moles of gas (1 mole of C2H4 and 1 mole of HCl) and end with 0 moles of gas (1 mole of C2H5Cl is a liquid). Therefore:

Δn = moles of gaseous products - moles of gaseous reactants = 0 - 2 = -2

Step 3: Calculate ΔE

Now we can substitute the values into the equation:

ΔE = ΔH - ΔnRT

First, convert ΔH from kJ to J:

ΔH = -723 kJ = -723,000 J

Now plug in the values:

ΔE = -723,000 J - (-2)(8.314 J/(mol·K))(300 K)

ΔE = -723,000 J + 4988.4 J

ΔE = -718,011.6 J

Step 4: Convert back to kJ

To express ΔE in kJ, we divide by 1000:

ΔE = -718.01 kJ

Thus, the change in internal energy (ΔE) for the reaction when 98 g of C2H4 and 1095 g of HCl are reacted at 300 K is approximately -718.01 kJ. This negative value indicates that the reaction is exothermic, meaning it releases energy to the surroundings.