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# Stoichiometry

### Find Molecular Formula

A Compound containing only carbon, hydrogen and oxygen was analyzed and found to contain 70.6% carbon, 5.9% hydrogen, and 23.5% oxygen, by mass. The molecular weight of the compound is 136 amu. What is the molecular formula? a. C8H4O b. C8H8O2 c. C9H12O d. C4H4O e. C5H6O2.

### Calculating Mass: Example Problem

What is the mass of Cu produced if 10.0 g of Cu2S reacts with 16.0 g of O2 as follows: (mass of one mole: Cu= 63.5 g, O = 16.0 g, S = 32.1 g) Cu2S + O2 -> 2Cu = SO2 a. 7.99 g b. 3.99 g c. 65.5 g d. 31.8 g

### Boiling Point Elevation of Chloroform

Boiling Point Elevation. What is the boiling point of a solution made by dissolving 0.7250 grams of C14H10 in 14.50 grams of chloroform (CHCl3)? The normal boiling point for chloroform is 61.70°C and its boiling point elevation constant is 3.63°C/m.

### Mass Assembly Questions

Fill in the blanks and please explain the steps to reach the solution. Experimental quantities: KCLO3 Mass of salt 4.5 - 5.0 g 1st quantity of water 10 g 2nd 2g 3rd 8g 4-5g 5-5g 6-10g Mass of assembly: 29.60 g Mass of assembly + salt+ water after 4th addition: 39.05 g Mass of assembly + salt 33.80 Problem: Mass o

### Empirical Formula of a Hydride

1. The phosphine that is produced by the reaction of water on calcium phosphide contains an impurity, another gaseous hydride of phosphorus, this hydryde contains 94% phosphorus and 6% hydrogen by mass. Calculate the emphirical formula using the percentages. 2. At 136.5C and a pressure of 760 mmHg, 0.22g of the hydride occup

### Rate of rxn given concentrations and rate constant

For the concentration of hydroxyl radical of 7.5E06 molecules/cm3 and a carbon monoxide concentration of 18 ppm, calculate the rate of its reaction with atmospheric carbon monoxide at 11 degrees C, given that the rate constant for the process is 5E-13 E-300/T molecule-1 cm3 sec-1. Hint: Convert the rate constant to a numerica

### Concentration and Molarity

A. Explain how to prepare 25 liters of a 0.10 M BaCl2 solution, starting with solid BaCl2. b. Specify the volume of the solution in (a) needed to get 0.020 mol of BaCl2.

### Using Avogadro's Number

How many H2O molecules are there in a snowflake weighing 1 mg?

### Using Avogadro's Number

Calculate the mass in grams of 2.5 x 10^9 H2O molecules.

### Electrolysis of water

By the electrolysis of water, 11.2 L oxygen at STP was prepared. A) What charge was required? B)If a current of 0.5A was used how long did it take?

### Calculate molar solubility

Calculate the molar solubility of AgCl in a solution made by dissolving 10.0 g of CaCl2 in 5.00 L os solution.

### Practice Quiz: Sum of the coefficients of balanced equation; Protons and electrons etc.

I just need the answer!!!!!!!! Question 36 Multiple Choice 20 points Atoms of the same element with different mass numbers are called: nucleons neutrons allotropes chemical families isotopes Question 37 Multiple Choice 20 points Which is the correct formula for copper(II)

### Theoretical Mass and Percent Yield

A) What is the theoretical mass of xenon tetraflouride that forms when 130 grams of xenon is reacted with 100 grams of flourine? b) What is the % yield if only 145 grams of xenon tetrafluoride is actually obtained?

### Cobalt by Volhard

Cobalt 2+ can be analysed by treatment with a known excess of thiocyanate in the presence of pyridine according to the equation: Co2+ + 4C5H5N + 2SCN- -------> Co(C5H5N)4(SCN)2 (s) The precipitate is filtered off, and the SCN- content of the filtrate is determined by Volhard titration. Lab Results: 25ml of unknown solu

### Finding the Concentration of Whiskey in m/v%

Add approximately 100cm^3 of water to 10cm^3 of whiskey - then fill up the flask to the 500cm^3 mark with water. Pipette 20cm^3 of this solution into a conical flask containing 70cm^3 of 0.05M acidic solution K2Cr2O7. Titrate the excess unreacted K2Cr2O7 with 24.82cm3 of 0.1268M Fe(II) solution. Find the concentration of the

### Calculation mass of alcohol in a solution (volume% is given)

A mouthwash contains 22.5% alchohol by mass. If the bottle of mouthwash contains 350 mL, what is the mass, in g, of alcohol? Using the (m/v)%= Mass of solute (g)X100 Volume of solution(mL) So far, I have: Step 1. 22.5% alcohol= 22.5g alcohol _________

### Aqueous Solution

A chemist needs 500 g of a 5% aqueous HCl solution. Describe how to make this solution. Show how to determine the amount of solute and solvent required, including all mathematical formulas and computations. Results must be labeled and include appropriate units for mass.

### Working with Osmotic Pressure

An aqueous solution of 10 g of catalase an enzyme found in the liver has a volume of 1 liter at 27 degrees Celcius. The solutions osmotic pressure at 27 degree celcius is found to be 0.745 torr. Calculate the molar mass of catalase. could you please explain how you come up with the answer to this problem? Thank-you.

### Combustion Reactions - Thermochemistry

1. A boiler burns fuel which has the following composition by mass: 82% carbon, 5% hydrogen, 6% oxygen and 7% ash. (a) Find the stoichiometric A/F ratio. If the dry analysis of the products yielded the following composition by volume: 13.2% carbon dioxide, 1.5% carbon monoxide, 6.8% oxygen and 78.5% nitrogen, calculate:

### Basic Chemistry Problems

Hi, I need some assistance understanding the answers to the following multiple choice questions: 1. The weight of a body varies according to the force of gravity exerted on the body. True False 2. An anion is the a: - Positive pole in an electrical system - Subatomic part of an atom - Molecule with a +1 net charge

### Mass, Volume and Density of unit cell of lead

Lead has an atomic radius of 175 pm and crystallizes in a face centered cubic structure. Find the mass of the unit cell in grams, thje volume of the unit cell in cubic centimeters, and the density of lead in g/cubic centimeters?

### What is the mass in grams of 1.00 X 10^12 lead (Pb) atoms?

What is the mass in grams of 1.00 X 10^12 lead (Pb) atoms?

### Chemical Properties of Lead and its Weighting within Water Samples

If a water sample is found to contain 0.015ppm of lead (Pb), how many grams of lead are in 3.00L of this water?

### Electronic Spectra in Coordination Chemistry

The most intense absorption band in the visible spectrum of [Mn(H20)6}2+ is at 24,900 cm-1 and has a molar absorptivity of 0.038 mol -1 cm-1. What concentration of [Mn(h20)6]2+ would be necessary to give an abosorbance of 0.10 in a cell of path length 1.00.

### 6 molar solubility

The Ksubletterssp for silver(l) phosphate is 1.8x10^-18. Calculate the molar solubility of silver phosphate. show all work and all steps. thanks

### Mole and Weight Percent Composition

Gas chromatographic analysis of a mixture of organic compounds gave the following peak areas (sq cm): hexane = 2.7; heptane = 1.6; hexanol = 1.8; toluene = 0.5. (a) Calculate the mole percent composition of the mixture. Assume that the response of the detector (area per mole) is the same for each component. (b) Calculate t

### Percentage AL and NH4AL(SO4)2 a Sample Before Filtering

The aluminum in a 1.200-g sample of impure ammonium aluminum sulfate was precipitated with aqueous ammonia as Al2O3*H20. The precipitate was filtered and ignited at 1000 degrees C to give anhydrous Al2O3, which had a mass of 0.1798g. a) What is the percentage of Al in the original sample? b) What is the percentage of NH4Al(

### Dehydrated Ethanol Reaction

At intermediate concentrations of H2S04 in the temperature range 140-170 degrees C, ethanol may be dehydrated by two different independent reactions (see attachment). Suppose that 30% of the ethanol reacts via reaction (1) and 70% via reaction (2). How many moles of water are produced per mole of original ethanol?

### Chemical Formula for Indium

At one time, it was thought that indium formed a chloride of formula InCl2. More recent work shows that the compound in question is actually In3[In2Cl9]. Determine the percentage by mass of indium according to each formula, and explain how the error could be made.

### Balancing Equations and Limiting Reagents

Using the initial concentration and volumes, how does one calculate the limiting reagent in each reaction below? {Please provide step by step solutions) 1# [0.1M]Pb(NO3)2 + [0.1M] Na2CrO4 --> ? initial volumes: 0.5 ml & 1 ml consecutively. 2# [0.1M]Pb(NO3)2 + [0.3M] Na3PO4 --> ? initial volumes: 1.5 ml & 0.25 ml con