Question

The combustion of ethyne, shown below unbalance, produces heat which can be used to weld metals:

C2H2 (g) +502 (g) →2CO: (g) +H20 (g) AH reaction= -1544kJ
How much ethyne gas (in g) would you need to react with excess oxygen according to this reaction in order to raise the temperature of 325 g of high carbon steel from 165'C to its melting point, 1540 C? The heat capacity of high carbon steel is 0.490 J/g'C. (Assume a complete reaction and that all heat is transferred from the reaction to the metal with no loss.)
a. 7.37g
b. 1.84 g
c. 4.13 g
d 3.69 g

Answer 1

3.69 g

Step-by-step explanation:

Given that:

The mass m = 325 g

The change in temperature ΔT = ( 1540 - 165)° C

= 1375 ° C

Heat capacity
`c_p` = 0.490 J/g°C

The amount of heat required:

q = mcΔT

q = 325 × 0.490 × 1375

q = 218968.75 J

q = 218.97 kJ

The equation for the reaction is expressed as:

`C_2H_(2(g)) + 5O_(2(g)) \to 2CO_(2(g)) + H_2O_((g)) \ \ \ \ \ \Delta H^o_(reaction) = -1544 \ kJ`

Then,

1 mole of the ethyne is equal to 26 g of ethyne required for 1544 kJ heat.

Thus, for 218.97 kJ, the amount of ethyne gas required will be:

`= (26 \ g)/(1544 \ kJ) * 218.97 \ kJ`

= 3.69 g