Share
Explore BrainMass

Stoichiometry

Finding atoms in a sample

Avogradro's number (6.022 x 10^23 atoms/mol) is a useful number that can be used to calculate a number of different values for compounds/elements. One important value is finding the number of atoms in a specific mass of an element. The solution includes a general step-by-step method of finding the number of atoms in a specific

Titration: Finding Percent CuSO4 in a Solution

Copper 2 ions can be determined by the net reaction 2Cu +2I- + 2S2O3)2----->2Cu(s)+S4O6)2- A 2.115-g sample containing CuCO4 and excess KI is titrated with 32.55ml of o.1214M solution of NA2S2O3. What is the percent CuSO4? (159.6/g mole in the sample)

Equations and Formulas

1. Write the equation for the decomposition of the hydrate, CuSO2*XH2O. 2. Record the following masses: (a) mass of the empty crucible (g): 53.200g (b) mass of the crucible and hydrate (g): 58.200g (c) mass of the crucible and pure salt (g): 56.396g 3. Calculate the following: (a) mass of wa

Moles to Moles

1. Record and calculate the following: (a) Mass of copper used in the reaction (g) 114.815g (b) Moles of copper used in the reaction (a simple stoichiometric conversion of mass to moles using the molar mass for copper of 63.5 g/mol. Show your work). (b) Mass of beaker and dry silver (g) 313.867

General Chemistry

Question 11.2 Which one of the following does not occur as diatomic molecules in elemental form? Bromine Nitrogen Hydrogen Sulfur Oxygen Question 12.2 Sulfur forms an ion with a charge of _______. +3

General Chemistry

Question 1 If matter is uniform throughout and cannot be separated into other substances by physical means, it is _______. a compound an element a homogeneous mixture either an element or a compound a heterogeneous mixture

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.

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.

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

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

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

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

Ions

Calculate the total number of ions in 14.6 g CaH2.

Reaction - Fluorine Gas

Elemental sulfur occurs as octatomic molecules, S8. What mass of fluorine gas is needed for complete reaction with 218.48 g sulfur to form sulfur hexaflouride?

Purity and Density of metals

Determination of density has many practical applications. Is a piece of jewelry pure gold or is it an alloy perhaps of gold and silver? Give that the densities of gold and silver at 25 degrees C are 19.3 and 10.5g/mL respectively and that the volume of the alloy is the sum of the volumes of the metals used, calculate the density

Density

1) A material will float on the surface of a liquid if the material has a density of less than that of the liquid. Given density of water as 1.0g/mL, will a block having a volume of 1.2*10^4 in^3 and weighing 350 lb float or sink? 2) The density of pure silver is 10.5g/cm^3 at 20 degrees C. If 5.25 grams of pure silver pell

Significant figures and conversions

Please give rules for significant figures and explain as go along. 1) Put in decimal form and in scientific notation with sig. figures. a) 4.060 + 120.23 + 4.1*10^-2 b) (140) / [7.2*10^3 * 16.43 * (16.43 - 14.26)] 2) How many sig. figures? a) 100 b) 1.0*10^2 c) 1.00*10^3 d) 100. e) 0.0048 f) 0.00480 g) 4.8

Solutions

A solution of sodium cyanide (NaCN)is prepared by dissolving 50 grams into 500ml of solution. What is the Molarity,%(w/v), and ppm of the resulting solution.