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# Stoichiometry

Stoichiometry refers to the study of relative quantities of reactants and/or products within a defined chemical system. It focuses on the relationships among quantities of reactants and products usually forming ratios of positive integers due to the nature of the bonded atoms. For example, in the combustion of methane (CH4), exactly 1 mole of methane reacts with 2 moles of oxygen to form 1 mole of carbon dioxide and 2 moles of water:

CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l)

Considering the relative abundances of reactants and products is a specific branch of stoichiometry called ‘reaction stoichiometry.’ In the example above, reaction stoichiometry describes the 1:2:1:2 ratio of molecules CH4, O2, CO2 and H2O. These ratios can be used to determine values such as the percentage yield of products under different conditions, the presence of a limiting reagent, and even predict the behavior of certain elements under experimental conditions.

Thus, understanding the fundamentals of stoichiometry can help calculate the desired quantitative data regarding chemical reactions, as well as other value which do not pertain to chemical reactions, such as the examination of elements within compounds and the behavior of gases.

## BrainMass Categories within Stoichiometry

### Stoichiometry problem to find number of moles

A mixture 20.2g of P and 78.2g of Cl2 reacts completely to form PCl3 and PCl5 as the only products. Find mass of PCl3 formed?

### Finding the formula of hydrates

Please explain how to calculate the formula of an unknown hydrate.

### Solutions, Precipitations, and Balancing Equations

1 - Presuming that these molecules are soluble, tell what ions are "produced" upon dissolving. Rb2SO4 NaC 2H3O 2 AlCl3 2 - Calculate the molarity of 13.2 g of NaOH dissolved in 250 ml of water 27 g of C6H 12O6 in 400 ml of water 3 - How many grams of BaCl2 would you need to make 200 ml of a 0.75 M solutio

### Gnuplot for Partial Density of States

I have partial density of states data I'd like to plot in the form of either (or both) of the attached documents, but I'm having some trouble figuring it out on gnuplot. I realized this is not a physics question, but I'm hoping someone has experience with making "stacked" plots of data. Note: I MUST use gnuplot. Please tell

### Chemistry Limiting problems

Please complete with worked out solutions to all problems

### Calculate mass octanol in 1 g gasoline

Assume the average American car is driven 7000 miles/year.How much carbon (in lbs) is released into the atmosphere by this car? Assume gasoline is octane, with a density of 0.692 g/mL. Assume the car mileage is 20 miles/gallon. Calculate mass octanol in 1 g gasoline. Calculate mass of C. Calculate gallons of gas used per year

### Molality and Molarity Questions

Question #1: For the reaction: 2 Al + 6 HBr (aq) ---> 3H2 + 2 AlBr3 What volume of 0.300 M HBr(aq) is needed to react with 22.6 g of AL? Question #2: The density of a 3.92 M solution of NaCl in water is 1.148 g/cm^3 at 20 degrees celcius. Find the molality (not molarity) of this solution.

### Ksp and Normality

Question #1 A student carries out a reaction in which the ion MnO4^- is reduced to MnO2. The student uses a 0.60 M KMnO4 solution. Find the normality of this solution. Explain the calculation. Question #2 If 200mL of .300M Cr(NO3)3 (aq) is added to 100 ml of 4.0 x 10 ^-4 M NaF(aq) at 25 degrees Celsius will CrF3 precipi

The following questions involve radiochemistry. Concepts covered include radiopharmaceutical question: looking at radionucleotide accumulation in the brain and mammogram photons. See the attached file.

### Freezing Point Depression of Water by Sucrose

We need to calculate the molar mass of sucrose from the freezing point depression of water using a MeasureNet temp probe to get the cooling curves of water and sucrose. We haven't covered "molality" yet, and I'm looking for a simple way to determine these values? I'm more than willing to do the work myself, I just need a push in

### Molecular Weight by Freezing Point Depression

For unknown sample #1, there is 2 g of the unknown sample and 10 mL of water. The freezing point was -1.7 C so Td=1.7. In unknown sample #2, there is 2g of the sample and 10 mL of water. Freezing point = -1.8. So Td = 1.8. How do I obtain the molecular weights for these two unknown samples?

### Precipitation Practice Problem

This problem gives a detailed solution on how to use the Ksp to calculate the maximum solubility to a neutralization solution. This sample uses as an example the reagents NH3 and MgCl2. To 0.350 L of 0.150 M NH3 is added 0.150 L of 0.100 M MgCl2 . How many grams of (NH4)2SO4 should be present to prevent precipitation of Mg(OH

### Calculating the volume, temperature, and density of liquids and gasses

a) Which of the following is not a unit of pressure? atm torr mm Hg Pascal all of these are units of pressure b) What device is used to measure atmospheric pressure? c) What pressure (atm) is exerted by a column of ethanol 55.0 cm high? The density of ethanol is 0.789 g/cm3 and 9.8m/s2 as your gra

### Stoichiometry worksheet

Question 1 What is the molar mass of propane (C3H8)? Use the average molar masses on the periodic table. Do not include units. Round to two decimal places. Question 2 What is the percent composition of carbon in sodium carbonate (Na2CO3)? Use the average molar masses on the periodic chart, do not include units, roun

### Density of Chloroform

Please see attachment and provide work so it can be use as reference! Density 1- Calculate the density of chloroform using the data in the picture below. 2- A glass sample bottle weighs 24.225 g when empty. When filled with carbon tetrachloride, CCl4, it weighs 28.715. If the density of carbon tetrachloride is 1.5842 g/m

### Properties of Solutions: Colligative Properties

Properties of Solutions 1. Anthraquinone contains only carbon, hydrogen and oxygen and has an empirical formula of C7H4O. The freezing point of camphor is lowered by 22.3oC when 1.32 g of antraquinone is dissolved in 11.4 g of camphor. Determine the molecular formula of anthraquinone. ( Kf for camphor is 40.0). 2. A solut

### Calculations: Volume, Density, Mass, Efficiency, Conversions

1. Calculate the volume of 235.1 g of mercury (D=13.5g/cm3). Round to one decimal place, do not include units in your answer. 2. The empty cylinder has a mass of 45.8 g. A liquid is added and the mass of the liquid and the cylinder is 107.2. What is the density of the liquid in the cylinder? Round to one decimal place; do not

### Measurement and Scientific Notation

1. In a density experiment, a student experimentally measures the following four values for the density of liquid ethanol: 0.772g/ml, 0.774g/ml, 0.785g/ml, and 0.775g/ml. The theoretical density of ethanol is 0.789 g/ml at 20ºC. a. Compute the average density of ethanol. b. Compute the % error for the average density (to 2 si

### Naming Chemical Substances

1 - What is the name of Ni(CH3CO2)3? 2 - What is the name of Al(HCO3)3? 3 - What is the name of Sn3As2? 4 - What is the name of MnSO4? 5 - What is the name of Co(CN)3? 6 - What is the name of CuF2? 7 - What is the name of BrO2? 8 - What is the name of CCl4? 9 - The chemical substances in the first column of the ta

### General Chemistry Problem Set

Please refer to the attached file for the questions. I would like to get answers for all the red highlighted questions. Part 1: The mole provides a convenient package where we can make a connection between the mass of a substance and the number (count) of that substance. This is a familiar concept if you have ever bought nai

### Methane and Oxygen Mixture at STP

What is the total pressure when 1.00 L of methane (CH4) at STP and 4.00 L of oxygen at STP are mixed in a 12.0-L container? If the mixture is ignited and the methane completely combusts, producing carbon dioxide (CO2) and water (H2O), calculate the mass percent, the mole fraction, and the partial pressure of CO2 in the container

### Salting Sidewalks

Living in Michigan, we are accustomed to having snow and ice on our sidewalks. Besides "chipping" the ice away, we add something (usually a salt) to the sidewalks and the ice melts. In addition, if we use calcium chloride rather than sodium chloride, we find we have to use less calcium chloride than sodium chloride to obtain th

### Molar Mass of a Compound

You dissolve 1.000 g of a compound in 100.0000 g of benzene and determine the freezing point of this benzene solution. This solution has a freezing point of 5.1686 EC; whereas, the freezing point of pure benzene is 5.4500 EC. The freezing point depression constant Kf = 5.070 EC/m, where m is the molality of the solution. What is

### Determining Radius of an Atom, Packing Efficiency and Molar Mass

You are the Science Office on the Starship Enterprise. While surveying an uninhabited planet, you find a new mineral containing only one element. X-ray analysis demonstrates that this mineral has a face-centered-cubic arrangement of atoms and an edge of the unit cell of 565.685 pm. The density of this mineral is found to be 11.0

### Determination of Formula (MgO)

Please see attached PDF to review the experiment. I'm looking for calculations to complete the table, and answers to the proceeding questions.

### de Broglie Wavelength of a Rifle Bullet

A certain rifle bullet has a mass of 8.13 g. Calculate the de Broglie wavelength of the bullet traveling at 1721 miles per hour. Physical constants are found below: Physical Constants Quantity Symbol Value speed of light in a vacuum c 2.99792458Ã-108 m/s (exact) Planck's con

### Molar Solutions - NaOH

Please show steps and provide a short explanation. The formula weight of NaOH is 40.0. 1. How many grams of NaOH are needed to make 1M solution? 2. How many grams of NaOH are needed to make a 0.5M solution? 3. How many grams of NaOH are needed to make 0.25M solution? 4. How many grams of NaOH are needed to make 500m

### The Molecular Formula of a Hydrocarbon

Question: A liquid hydrocarbon is found to be 16.37% H by mass. A 1.158-g vaporized sample of the hydrocarbon has 385-mL volume at 71.0 °C and 749 mmHg. What is the molecular formula of the hydrocarbon?

### Chemistry Questions: "A water solution has 1.00x10-3 moles of H+ in 10.0L of solution."

Note: 1. Please clearly show all steps of logical solutions. 2. Be sure to give answers correct units and significant figures. 1.True or false A. All compounds that contain hydrogen are acids. B. A solution with pH 5 has 10 times higher [H+] than a solution with pH 6. C. SO3 in the atmosphere is one cause of

### Calculation Based on Purifying Groundwater

Perchloroethylene is an industrial solvent that can be used for metal degreasing. If 2000 L of perchloroethylene were accidentally leaked into the environment and entered the groundwater, how many tonnes of iron would be needed to purify the groundwater using an underground permeable wall? (perchloroethylene density = 1.623 g/mL