Explore BrainMass


Gas stoichiometry

C2H5OH burns in air: C_2H_5OH(l)+O_2 --->CO_2(g)+H_2O(l) balance the equation and determine the volume of air in liters at 35.0 C and 790 mmHg required to burn 227 g of ethanol. assume that air is 21.0 percent O_2 by volume.

the percent silver of the dime in the oxidation reaction

For my AP chemistry lab, I was supposed to find the percent of silver in a dime. I started out with the formula: Ag + NaCl → AgCl +Na. The dime was put in a covered beaker with NaCl. However, during the experiment oxygen was added as one of the reactants, accidentally. The precipitated silver chloride was obviously con

Mass percentage of sodium chloride in a mixture

A sample of a mixture containing only sodium chloride and potassium chloride has a mass of 3.5650g. When this sample is dissolved in water and excess silver nitrate is added, a white precipitate (silver chloride) forms. After filtration and drying, this precipitate has the mass 7.9143g. What is the mass percentage of sodium ch

Calculating PPM Saline Solution

The chloride in a saline solution was determined by the Volhard method. A 25 ml aliquot of the solution was acidified with 2 ml of dilute HNO3 and treated with 25 ml of .1749 M AgNO3 (fw 169.9), causing precipitation of AgCl. After addition of several ml of nitrobenzene, the solution required 26.40 ml of .1575 M KSCN to reach t

Find the mass percent of Tl2SO4.

The thallium (present as Tl2SO4) in a 7.80-g pesticide sample was precipitated as thallium(I)iodide. Calculate the mass percent of Tl2SO4 in the sample if 0.890g of TlI was recovered.

Mass of a Reactant

See the attachment for the full problem statement. Finding the mass of a reactant in an industrial equation: Cu(NH3)4Cl2(aq) + 4 NH3(aq) + Cu(s) --> 2 Cu(NH3)4Cl(aq)

Atomic masses: relative abundance

The element Europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 amu, and 153Eu has a mass of 152.9209 amu. The average atomic mass of europium is 151.96 amu. Calculate the relative abundance of the two europium isotopes.

Density and Number of Atoms

The Density is 7.87g/cm^3 , and the average mass for a single iron atom is 9.28*10^-23g . How many iron atoms are present in an iron bar whose dimensions are 2.00 cm * 3.00 cm * 8.00 cm ?

Density Material of a Length

A cube of material with a length of 0.044 m and mass of 10.00 X 10 to the negative 1 power kg. What is the density (g/mL)?

Empirical formulae - the uses

A 1.000g sample of an unknown hydrocarbon containing only carbon and hydrogen is burned in excess oxygen to yield carbon dioxide and water. The masses of CO2 and H2O are 2.994g and 1.635g, respectively. What is the empirical(simplest) formula for this compound?

Nuclear Reaction Question

In spontaneous nuclear reactions: a. the products weigh less than the reactants b. the products weigh more than the reactants c. the difference in mass between reactants and products is zero d. mass is converted to light e. the products move at the speed of light squared

Finding molarity and the reactions and productions of a balanced equation

1.) What is the molarity of a solution made by dissolving 25.6 g of KOH (5601 g/mol) in enough water to make 3.00 L of solution? 2.) 2 Fe + 3 Cl2 ------> 2FeCl3 How many moles of Fe are needed to produce 76.4 g of FeCl3 (162.3 g/mol)? How many grams of Fe (55.8 g/mol) are needed to react with 123 g or cl2 (71.0 g/mo

Multiple choice question about the relationship between Q and Kp.

If the value of Q is greater than Kp, then a. the system is in equilibrium b. the reaction will proceed to the right until equilibrium is established c. a catalyst is necessary to achieve equilibrium d. the reaction will go left or right depending on the reaction stoichiometry e. the reaction will proceed to

Chemistry multiple choice questions (chem-2)

1. A collection of atoms, molecules, or ions that contains Avogadro's number of these items is called what? 2. The initial substances that undergo change in chemical reaction are called what? 3. The law that states that atoms are neither created nor destroyed in a chemical reaction, but may be rearranged, is called what? 4. T

Weight loss during nuclear fission reaction

The nuclear fission energy for the isotope U-235 is 1.67x10^10 kJ/mole. What is the mass of the fission products produced from 1.000 kg of radioactive material U-235? What is the percent weight loss?

Average Molar Atomic Weight of Chlorine

What is the average molar atomic weight of chlorine, if the natural abundance of Cl-35 and Cl-37 isotopes are 75.4 molar % and 24.6 molar %, respectively? M(Cl-35) = 34.969 g/mole M(Cl-37) = 36.966 g/mole.

percentage concentration of two solutions in regards diffusion

You have a mixed solution in a beaker which contains a bag of 4g dissolved in 15ML of water. The beaker contains 50g of glucose dissolved in 200mL of water. What is the percentage concentration of the two solutions? Does the glucose diffuse out or into the bag? And what will happen to the water?

Calculating moles, molar mass and molecular weight

The chlorophyll-a molecule, C55H72MgN4O5, is important in photosynthesis. (a) Determine its molecular mass (in atomic mass units) (b) What is the mass (in grams) of 3.00 moles of chlorophyll-a molecules?

Determining the formula of a hydrate.

When all of the water of hydration was driven off of 4.32g of a hydrate of compound Z, the residue, the anhydrous form of Z, had a mass of 3.09g. What is the formula of the hydrate (using the symbol Z as part of it)? The formula mass of Z is 90.0

Mixture- identity of metals

When 8.900 g of a mixture of an alkali metal chloride (XCl) and an alkaline earth chloride (YCl2) was dissolved in 150.0g of water, the freezing point of the resultant solution was -4.42C. Addition of an excess of aqueous AGNO3 to the solution yielded a white precipitate with a mass of 27.575 g (This white precipitate would be