Exam (elaborations)
CHEM 120 EXAM 3 QUIZ STUDY CORRECTLY ANSWERED AND RATED A
- Course
- Institution
CHEM 120 EXAM 3 QUIZ STUDY CORRECTLY ANSWERED AND RATED A
[Show more]
Content preview
CHEM 120 EXAM 3 QUIZ STUDY CORRECTLYANSWERED AND RATED A
1.
Question: Magnesium reacts with oxygen to form magnesium oxide, and the
following balanced chemical equation is given: 2 Mg + O₂ → 2 MgO. How many
moles of MgO are produced when 4 moles of O₂ react completely?
Correct Answer: 8 moles
Explanation: According to the balanced equation, 1 mole of O₂ reacts with 2
moles of Mg to form 2 moles of MgO. Therefore, 4 moles of O₂ would produce 8
moles of MgO.
2.
Question: (a) Determine the number of atoms for each element present in the
following molecule: Cu(CN)₂.
(b) Using the periodic table of elements, determine the molar mass for this
molecule. Show your work.
Correct Answer:
(a) Number of atoms:
• Cu = 1
• N=2
• C=2
(b) Atomic Mass:
• Cu = 63.546
• N = 14.007 (2)
• C = 12.01 (2)
Molar Mass: 115.6 g per mole
Explanation: To calculate the molar mass, sum the atomic masses of
each element in the molecule based on their quantities in the formula.
, 3.
Question: (a) Determine the number of atoms for each element present in the
following molecule: Mg(NO₃)₂.
(b) Using the periodic table of elements, determine the molar mass for this
molecule. Show your work.
Correct Answer:
(a) Number of atoms:
• Mg = 1
• N=2
• O=6
(b) Atomic Mass:
• Mg = 24.305
• O = 15.999
• N = 14.007
Molar Mass = 148.31 g per mole
Explanation: This involves counting the atoms in the formula and using
the atomic masses to calculate the molar mass.
4.
Question: You were asked to calculate the concentration of a NaCl (in water)
solution in several ways and are given the following information:
• 30 g NaCl
• 300 mL solution
• Molecular weight of NaCl = 58.44 g/mol
(a) Calculate the mass/volume percent concentration.
(b) Calculate the molarity of the solution.
Correct Answer:
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 saraciousstuvia. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
80467 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now