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# Stoichiometry

### Sodium Chloride Solution

Determine how many grams of NaCl are required to prepare 500 mL of a 0.15 M NaCl solution? Hint: The formula mass of NaCl (sodium chloride) is 58.5 amu.

### Molarity of water

Calculate the molarity of one litre of water.

### Volume of Cyclohexane Should be Used

After a label fell off a bottle containing a clear liquid which is believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0 ml portion of the liquid had a mass of 21.95g. A chemistry handbook lists the density of benzene at 15 degrees celcius 0.8787g/ml. Is the calculated density in agr

The best means of personal protection from radiation for emergency responders is the implementation of three basic principles: time, distance and shielding. Please show your work when answering the following questions: a. Using the inverse square law of radiation, what Geiger counter reading would you get for a radioactive m

### Chemistry: Mass of Calcium Hydroxide, Molarity of Sodium Urate

1. What mass of calcium hydroxide would be required to neutralize 125 ml of 1.5 M HCL?(aq) 2. Solubility of sodium urate is 0.067g/l, what is the maximum molarity of sodium urate in solution? Formula is NaC5H3N4O3

### Temperature of Carbon Monoxide Sample

Carbon monoxide is present at a level of 16.3 ppm by volume in an air sample taken at 15 degrees Celcius and 1.00 atm. At what temperature (at 1.00 atm pressure) would the sample also conatin 7.5 mg/cm^3 of CO? Can PV=nRT be used for this equation? If so, how does it relate to the 7.5 mg/cm^3?

### Osmotic Pressure Calculation

What is the osmotic pressure of 20g glucose in 100g water? What is the osmotic pressure of 20g sucrose in 100g water? (the actual values, not that found from P=iMRT) Please explain how you arrived at the answer.

### Chemistry Problems: Glucose and Ethanol

1. C6H12O6= 2C2H6O+2CO2 a. How many moles of glucose are required to produce 185 g of ethanol? b. How many grams of ethanol would be formed from the reaction of 0.325kg of glucose? 2. Person contains 60% water by mass. If a person weighs 60 kg, how many moles of water are present in this person's body?

### Volume of Water and Body Density

50 kg person is immersed in a water tank for body fat testing, she has an underwater mass of 2kg. This difference in body mass is equal to the mass of water displaced by the body. The density of water 1.00g/ml. a) what is the volume of the water displaced? b) what is the volume in liter, of the person's body? c) what is the

### Mass of Iridium in Grams

What is the mass in grams for a 1000ml volume of iridium if it has a density of 22.42g/ml? I think the answer is 22,420 grams. It seems too easy and I'm not sure if the weight of iridium is to be considered in the solution?

### Finding empirical formula from percent composition

What is the empirical formula of a compound that is 21.96% S and 78.04% F by weight?

### Molality and freezing point changes

1 - What is the molality of a solution of 89.5g of C12H22O11 in 895 grams of water? 2 - Will the solution in 1) have a lower, higher, or the same freezing temperature as pure water. Give a reason for your answer. Thanks!!

### Weapons of Mass Destruction

I'd like to get some outside conversation on the following question. Why do you think the issue of Weapons of Mass Destruction is an important topic and how does it impacts on the global community?

### Mass of Na2CS3 produced in the reaction.

For the reaction, given below, how many grams of Na2CS3 are produced in the reaction of 65 mL of liquid CS2 (d=1.26 g/mL) and 1.56 mol NaOH?3CS2 + 6NaOH -> 2Na2CS3 + Na2CO3 + 3H2O we can make calculations to determine the amount of reactant we need, or the amount of product we can expect to be produced in a chemical reaction.

### The Freezing Point of a Solution of an Unknown Substance

Add 2g of the unknown solid #1 and 10 mL of water to the test tube. the constant temperature bath is still set to dry ice. Drag and drop the constant temperature bath onto the test tube containing the solution. Repeat the measurement of the freezing point with unknown solid #2 using a new clean test tube. As with solid #1 use

### Electrolysis of a solution

Electrolysis of a solution containing an unknown metal ion with a +3 charge deposited 0.159 g of the metal on the cathode over a period of 2.00 minutes at a constant current of 2.00 A. What is the molecular weight of the unknown? A) 207 g/mol B) 192 g/mol C) 128 g/mol D) 21.3 g/mol E) 63.9 g/mol

### Molality, boiling and freezing of solutions: Example questions

What is the freezing point, boiling point, and molality of a solution with 150 grams of aluminum chloride dissolved in 350 mL of water? How much ethyl alcohol, C_2H_5OH is needed to dissolved 75 grams of naphthalene, C_10H_8 and produce a 0.1 molal solution? How many litres of water would be needed to dissolve 25 grams of

### Concentrations of Solutions Molarity and Molality

Part A A solution contains 0.173g of glycerol, C3H8O3, and 20.0 g of water. The density of water is 1.00g/mL What are the Molarity, Molality and % m / m concentrations of the solution? Part B What are the boiling and freezing points of the solution that has a molality of 0.062?

### Calculating yield from the mononitration of bromobenzene

The o:p ratio in the mononitration of bromobenzene has been reported to be 38:62. Use this ratio and the amount of 4-bromonitrobenzene actually isolated to estimate the experimental yield of mononitration in the reaction. What errors are there in using this method to calculate the extent of mononitration? The actual isolated amo

### Stoichiometry: number of atoms per mass, electrons per volume

How does one calculate: a) the number of atoms per mass of an element? b) The number of electrons per volume of an element? Please show the units for each factor i. e. Avogadro's number, Atomic Number, Atomic Mass, etc.

### Finding the Density of a Liquid

A student adds 14.9 mL of a liquid to a graduated cylinder that weighs 150.0 g when empty. After addition of the liquid the mass of the graduated cylinder is 175.05 g. What is the density of the liquid?

### Chemical Reactions: Stoichiometry and Metals

1. Calculate the molar mass of the following compounds: a. sodium selenide b. Palladium (II) hydroxide 2. Calculate the number of grams in each of the following compounds: a. 4.0 moles of CaCl2(s) b. 0.467 moles of (NH4)CO3(s), baking powder 3. Calulate the number of moles in each of the following compounds: a. 150.0

### Molecular Compounds

A molecular compounds dissolves in water to give up H+ ions and SO4^2- ions. If the compounds dissolved was HSO4^-, what mass of SO4^2- exists in the solution if 10 moles of it were dissolved? a) 96.07 g b) 130.22 g c) 192.14 g The answer I came up with is (a), but what about the 10 moles. (a) is the mass of the c

### How to do Mole Conversion Problems By Dimensional Analysis

This handout shows 13 completely worked examples of problems that feature mole conversions. All problems are performed using the dimensional analysis method, which focuses on the canceling of units to yield the desired result. Problem types include moles to grams, grams to moles, atoms to grams, grams to liters of a gas at STP,

### What mass of formaldehyde gas (in grams) must be released

What mass of formaldehyde gas (in grams) must be released from building materials, carpets, etc. in order to produce a concentration of 0.50 ppm of the gas in a room having dimensions of 4.0m X 6.0m X 2.0m?

### Given that the average TEQ of animal-based foods is about 0.9 picograms of TCDD equivalent per gram, and that the LD50 for 2,3,7,8-TCDD is about 0.001 mg/kg body weight, what mass(kg) of animal-based food would you have to consume to ingest a fatal dose of it?

Given that the average TEQ of animal-based foods is about 0.9 picograms of TCDD equivalent per gram, and that the LD50 for 2,3,7,8-TCDD is about 0.001 mg/kg body weight, what mass(kg) of animal-based food would you have to consume to ingest a fatal dose of it?

### Annual Increase in Concentration: Example Question

Given that the atmospheric burden of carbon dioxide increases by about 2.8 Gigatonnes annually, calculate the annual increase in its concentration on the ppm scale. Note that the atmospheric mass = 5.1E21g; air's average molar mass = 29.0 g mole-1.

### Base Peak in a Mass Spectrum

Which of the following statements best describes the base peak in a mass spectrum? a. The peak from the most stable radical. b. The peak from the species that has the isotope with the highest atomic number. c. The peak of highest intensity. d. The peak from the molecule minus an electron.

### Determining the amount of gasoline needed for combustion

How many liters of air (78 percent N2, 22 percent O2 by volume) at 20 degreesC and 1.00 atm are needed for the complete combustion of 1.0 L of octane, C8H18 a typical gasoline component that has a density of .70g/mL?

### Calculate Kp and Kc using Percent Dissociation

2 NOBr(g) = 2 NO(g) + Br2(g) If nitrosyl bromide, NOBr, is 34 percent dissociated at 25°C and the total pressure is 0.25 atm, calculate Kp and Kc for the dissociation at this temperature. How do I work dissociation into the Kc equation?