Explore BrainMass

Composition Stoichiometry

Composition Stoichiometry refers to the examination of the relative abundances of elements within chemical compounds. In order to use composition stoichiometry to calculate the desired quantitative data, it is important to understand the relationships between the elements in chemical compounds. This requires knowing how the atoms are bonded, and by extension its chemical formula.

For example, methane (CH4) has one central carbon with covalent bonds to four hydrogen atoms with each bond separated by 109.5 degrees in three dimensional space. So considering composition stoichiometry, the molar ratio of carbon to hydrogen would be 1:4. Thus, if there were four moles of carbon in a sample of methane, then it can be calculated using composition stoichiometry that there would be 16 moles of hydrogen.

However, since carbon is twelve times heavier than hydrogen, the mass ratio is 12:4, or more simply, 3:1. Thus, if there were 0.12 grams of carbon in a sample of methane, then based on the mass ratio, it can be calculated that there would be 0.04 grams of hydrogen.

Therefore, understanding the relationships between elements within compounds is absolutely fundamental for compositional stoichiometric calculations.

Stoichiometry Problems and Chemical Equations

I am a bit stumped with the following word problems, and am having trouble setting up the appropriate equations. If anyone can guide me in the right direction, or suggest ways on how to set up the right equations, I would greatly appreciate it: 1) Calculate the weight of 50% NaOH solution required to prepare 500 ml of 0.1 M N

Molar Concentrations in Nonpolar Solvents

In nonpolar solvents, benzoic acid tends to dimerize by forming hydrogen bonds between the carboxylic acid groups (see attachment) a. At T = 298K in benzene, the equilibrium constant for the dissociation of the dimer (see attachment) (C6H5COOH)2 2 C6H5COOH has the value Kc = 2.60 x 10-2. I

Ions in water

Hi there. I am unsure of how to do this question. It's question 4.102 in Chemistry: The Central Science 11E. Hard water contains Ca 2+, Mg 2+, and Fe 2+, which interfere with the action of soap and leave an insoluble coating on the insides of containers and pipes when heated. Water softeners replace these ions with Na +. If

Stoichiometry and Solute Concentrations

I am unsure of how to answer this question, 4.68 in Chemistry: The Central Science 11E a) How many grams of solute are present in 50.0 mL of 0.488 M K2Cr2O7? b) If 4.00 g of (NH4)2SO4 is dissolved in enough water to form 400 mL of solution, what is the molarity of the solution? c) How many millilitres of 0.0250 M CuSO4

Stoichiometry Problems

Please see the attached file for the complete problems. "Activity - Stoichiometry Exercises" 1. 1a. How many atoms are in 12 molecules of glucose. 1a. How many atoms are in 12 molecules of glucose, C6H12O6 ? Use exact value for this answer. 24 2. 1b. How many moles of fluorine gas (F<sub>2</sub> molecule)?

Assorted Stoichiometry and Theoretical Yield Problems

1) What is the weight percentage of C in C6H12O6? Report your answer to 3 significant figures. 2) What is the molar mass of TiCl4? Report your answer to two decimal places. 3) 20.0g of each Fe2O3 and Al are mixed together and react according to the following equation. What is the theoretical yeild of Fe? Report your answer in

Calculating moles when given amount of atoms

A (N2H5)2 C3H4O4 has 1.084 x 10^24 carbon atoms. ? moles of hydrogen atoms are there in this sample The atomic weight of hydrogen is 1.00794 There are 10 hydrogen in the given sample which is = 10.0794 atomic weight within the sample. How do I use the amount of carbon atoms to determine how many moles of hydrogen atoms are