# What is the standard enthalpy of reaction when 6.45g of acetylene are consumed?

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Acetylene can be formed by the following reaction:

#CaC_2(s)+5O_2(g)rarrC_2H_2(g)+Ca(OH)_s(s)#

Calculate #DeltaH_(rxn)# when 6.45g of #C_2H_2# are consumed in the equation below:

#2C_2H_2(g)+5O_2rarr4CO_2(g)+2H_2O(g)#

Acetylene can be formed by the following reaction:

Calculate

##### 1 Answer

#### Explanation:

You can calculate the enthalpy change of a reaction by using the **enthalpies of formation** of reactants and products.

The formula is

#color(blue)(bar(ul(|color(white)(a/a)Δ_text(rxn)H° = Δ_text(f)H_text(products)^@ - Δ_text(f)H_text(reactants)^@color(white)(a/a)|)))" "#

**Step 1. Calculate #Δ_text(r)H^@"# for 1 mol of reaction**

**Step 2. Calculate #Δ_text(r)H# for 6.45 g of #"C"_2"H"_2#**