Stoichiometry

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Balancing a stoichiometric equation.

Write the stoichiometric equation for magnesium nitride plus water that yields magnesium hydroxide and ammonia gas.

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)?

Dimensional Analysis: Density

What is the density of a 100.000 grams cubic object that has a length of 0.025 meters?

Converting ppm to micrograms.

If a patient has 0.08 ppm lead in their blood, how many micrograms would be contained in a liter of blood?

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.

Amount of coulombs required to deposit a required amount of mass

How many coulombs of charge are required to deposit 2.00g of Fe(s) from a solution of Fe3+?

Important information about solubility

1.) What volume of water is needed to completely dissolve 1g of AgBr in Liters? 2.) What is the water solubility of AgCl in gams per liter?

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?

Working with the mass of atoms in relation to earth's mass.

Earth has a mass of 5.98 x 10^24 kg. The average mass of atoms that compose earth is 40u. How many atoms in the earth?

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

Calculating how many moles are present in a solution.

How may moles of ions are present in 500 mL of a 0.400 M solution of aluminum sulfate, (Al2(SO4)3)?

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

Understanding limiting reagents.

How do you find the limiting reagent and how much the other one is in excess?

Calculating moles from the number of atoms

How many moles of Pb are in 9.3*10^15 atoms of Pb?

Determining the limiting reactant based on the chemical equation and the available quantity of the reactants.

For the balanced reaction: N2H4 + 2H2O2 = N2 + 4H2O 12.0 g N2H4 is reacted with 23.0 g H2O2. Which is the limiting reactant?

Balancing a chemical equation and calculating the reactant quantity based on the reaction stoichiometry.

Balance the following equation: Cu(s)+ AgNO3(aq) = Ag(s) + Cu(NO3)2(aq) ("s" and "aq" in parantheses refers to the phase of the reactants and products, i.e. solid and aqueous, respectively.) What is the amount of Cu (in grams) necessary to precipitate 0.50 g of Ag in the presence of excess AgNO3?

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