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Stoichiometry Problem Exercise for Chemistry Laboratory | CHEM 1110, Lab Reports of Chemistry

Roane State Community College Chemistry

Material Type: Lab; Class: General Chemistry I; Subject: Chemistry; University: Roane State Community College; Term: Unknown 1989;

Typology: Lab Reports

Pre 2010

Uploaded on 08/18/2009

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Stoichiometry Problem Exercise for Chemistry Laboratory

Do not hand in this work sheet. When you are ready, you will be given an examination over this

material. Complete the examination by yourself and hand it in to receive credit.

1. Calculate the number of moles in the following masses:

A) 10.0 g NH3 0.588 mol

B) 35.0 g CO2 0.795 mol

C) 25.0 g C3H7OH 0.416 mol

D) 0.020 g H2O 0.0011 mol

2. Calculate the number of grams corresponding to each of the following.

A) 0.015 mol of O2 0.48 g

B) 3.0 mol H2 6.0 g

C) 1.5 x 10!5 mol H2O 2.7 × 10!4 g

D) 25.0 mol C2H5OH 1.15 × 103 g

3. Calculate the number of molecules corresponding to the masses:

A) 10.0 g NH3 3.54 × 1023 molecules

B) 35.0 g CO2 4.79 × 1023 molecules

C) 25.0 g C3H7OH 2.51 × 1023 molecules

D) 0.020 g H2O 6.68 × 1020 molecules

Partial preview of the text

Download Stoichiometry Problem Exercise for Chemistry Laboratory | CHEM 1110 and more Lab Reports Chemistry in PDF only on Docsity!

Stoichiometry Problem Exercise for Chemistry Laboratory Do not hand in this work sheet. When you are ready, you will be given an examination over this material. Complete the examination by yourself and hand it in to receive credit.

Calculate the number of moles in the following masses: A) 10.0 g NH 3 0.588 mol B) 35.0 g CO 2 0.795 mol C) 25.0 g C 3 H 7 OH 0.416 mol D) 0.020 g H 2 O 0.0011 mol
Calculate the number of grams corresponding to each of the following. A) 0.015 mol of O 2 0.48 g B) 3.0 mol H 2 6.0 g C) 1.5 x 10!^5 mol H 2 O 2.7 × 10!^4 g D) 25.0 mol C 2 H 5 OH 1.15 × 10^3 g
Calculate the number of molecules corresponding to the masses: A) 10.0 g NH 3 3.54 × 10 23 molecules B) 35.0 g CO 2 4.79 × 10 23 molecules C) 25.0 g C 3 H 7 OH 2.51 × 10^23 molecules D) 0.020 g H 2 O 6.68 × 10 20 molecules

For the reaction:

2C 3 H 7 OH + 9O 2! 6CO 2 + 8H 2 O

A) Calculate the number of moles of CO 2 produced from 0.600 mol C 3 H 7 OH reacting with sufficient O 2. SET-UP

ANS 1.80 mol B) Calculate the number of moles of O 2 reacting with sufficient C 3 H 7 OH required to produce 3.60 mol of H 2 O. SET-UP

ANS 4.05 mol C) Calculate the number of moles of O 2 required to react with 1.80 mol C 3 H 7 OH. SET-UP

ANS 8.10 mol

(^1) Mass % is being discouraged by IUPAC at the moment, with the replacement being mass fraction, w , which is given by the formula: where i is included in the exhaustive j. However, %, which is always mass percent unless otherwise stated, is still very prevalent.

KClO 3 decomposes upon heating to form KCl and O 2. The reaction is:

2KClO 3! 2KCl + 3O 2

How many grams of KClO 3 must be heated to form 24.6 grams O 2? SET-UP

ANS 62.8 g

The percent yield is defined as the mass of the material actually recovered from a reaction divided by the mass calculated from the reactants times 100 %. The equation is: (^1). The calculated amount in the previous question was 24.6 g O 2. If one had actually recovered 20.0 g of O 2 , what would the percent yield have been?

ANS: 81.3 %

Using the reaction given in question 5, calculate the percent yield if one used 250.0 g of KClO 3 to produce O 2 , and was able to recover 84.2 g of O 2.

ANS: 86.0 %

Phosphoric acid (H 3 PO 4 , molar mass 98.0) can be prepared from P 4 and O 2 by the following series of reactions. P 4 + 5O 2! P 4 O 10 P 4 O 10 + 6H 2 O! 4 H 3 PO 4 16.5 grams of H 3 PO 4 were formed by reacting 0.0500 mole of P 4 with sufficient O 2 and H 2 O. Calculate the percent yield. SET-UP

ANS 84.2 %

Percent purity is defined as mass of pure material (or material of interest) divided by the total mass of material present times 100 %. The equation for this is: .

A sample consists of 55.0 g of salt and 35.0 g of sand. What is the purity of the salt?