Summary
Summary Enthalpy lab reports
- Course
- Institution
Lab report for enthalpy from time4learning edgenuity
[Show more]
Seller
Follow
Content preview
Enthalpy Lab ReportPurpose: Explore the enthalpy of the combustion of magnesium using Hess’s law.
Question: How can you use Hess’s law to determine a reaction’s enthalpy when you can’t do so using a
calorimeter?
Summary: The combustion of magnesium has the equation Mg(s) + 1/2O2(g) → MgO(s). This reaction gives
off enough heat that it could melt a coffee cup calorimeter, making it difficult to compute the enthalpy of the
reaction directly. However, you can do so indirectly using Hess’s law and the following three intermediate
reactions:
Reaction 1: Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Reaction 2: MgO(s) + 2HCl(aq) → MgCl2(aq) + H2O(l)
Reaction 3: H2(g) + 1/2O2(g) → H2O(l)
I computed the enthalpy of the Reactions 1 and 2 using a coffee cup calorimeter. The enthalpy of the third
reaction is well known (–286 kJ/mol). With these three enthalpy values, I used Hess’s law to compute the
enthalpy of magnesium combustion.
Data:
Measurement Reaction 1 (Mg + HCl) Reaction 2 (MgO + HCl)
Mass of HCl (g) 100.50 100.57
Mass of solid (g) 0.20 1.57
Total mass of reactants 100.70 102.14
Initial temperature (C) 22.5 22.7
Temperature furthest from initial 31.3 30.2
temperature (C)
Delta Temperature (C) 8.8 7.5
Heat released (J) 3700 3200
Moles of solid reactant (mol) 0.00823 0.0390
(Mg: 24.3 g/ mol) (MgO: 40.3 g/ mol)
Enthalpy of reaction (KJ/ mol) -450 -82
Reaction equation Delta H (kJ/mol)
Mg(s) + 2HCl(aq) ⟶ MgCl2(aq) + H2(g) -450
MgO(s) + 2HCl(aq) ⟶ MgCl2(aq) + H2O(l) -82
H2(g) + 1⁄2O2(g) ⟶ H2O(l) -286
Mg(s) + 1⁄2O2(g) ⟶ MgO(s) -654
Percentage error : 8.62%
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller caithlynong. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.89. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
81298 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now