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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?

Limiting reactants

Suppose 358 g aluminum sulfide react with 124 g water. Al2S3 + H2O -> Al(OH)3 + H2S unbalanced! What mass of the excess reactant remains?

Density Problem

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

Using Stoichiometry to Solve for Moles

Reaction: CO(g) + 2H2(g) -> CH3OH(g) Questions: 1) How many moles of each reactant are needed to produce 3.60 X 10^2g of CH3OH? 2) What are the number of grams of each reactant needed to produce 4.00 moles of CH3OH? 3) How many grams of hydrogen are necessary to react with 2.85 moles of CO?


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


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.


A serial dilution is used to prepare solutions containing amounts(grams)of chemicals so small that they would be impossible to measure with ordinary balance. If 5.00ml of a .10 Molar salt (NaCl) solution is diluted to 500ml,then diluted to 500ml of another new solution, what is its concentration. If 5.00 ml of this solution is d

Brackett Series

1) Lines in the Brackett series of the hydrogen spectrum are cause by emission of energry accompanying the fall of an electron from outer shells to the fourth shell. The lines can be calculated using the Balmer-Rydberg equation. See Attachement for equation where m = 4, R = 1.097 x 10-2nm-1 , and n is an integer greater th


Nickels are composed of 25% nickel and 75% copper by mass, what is its density (d of nickel = 8.902 g/cm3; d of copper = 8.95 g/cm3)?


The environmental protection agency (EPA) has proposed a new standard for microparticulates in air: For particles up to 2.5 um in diameter, the maximum allowable amount is 50 ug/m3. If your 9.2 ft x 13.8 ft x 8.6 ft dorm room just meets the new EPA standard, how many of these particles are in your room? (Assume the particles are

Concentration of Particles in Air

If a person breathes in 20m3 of air per day and the air contains 263 micrograms of particulates per m3, how many grams of particulates does a person breathe in per day?

Coal combustion

A particular coal contains 5.45% by weight of sulfur. How many grams of SO2 gas will be produced when 100.0g of the coal is combusted? S(s) + O2(g) SO2(g)

Calculating a Compound's Solubility

Question: Consider a body of water in equilibrium with solid calcium sulfate (CaSO4), for which Ksp = 4E-5 at 25 degrees Celsius. Calculate the solubility of calcium sulfate in water (in grams/liter) assuming that the other reactions are negligible.

Calculating the number of moles and from the compound's mass.

First, how many moles are present in each of the following masses? 2.58g of SrSO4 and 2.53 x10-3g of Ag2CO3. Second, going in reverse, How many grams are necessary to obtain the given number of moles? 3.20 x 10-4 moles of NaOH and 6.42 moles of AgNO3.


What does a radon level of 3pCi/L in a home mean. Should you be concerned about a radon exposure at this level? Why or Why not?

Hydroxide ion concentration using K or Kw not Ksp

At 25 degrees C, 0.212 g of barium hydroxide Ba(OH)2 (2 in lower position) is dissolved completely in sufficent water to make 0.25 litre final solution. What is the hydroxide ion concentration(in mol per litre) in this solution? Give the answer in scientific notation to an appropriate number of significant figures, and sta

Osmotic pressure and molar mass

An aqueous solution of 10.00 g of an enzyme has a volume of 1.00 L at 29°C. The solution's osmotic pressure at 29°C is found to be 0.781 torr. Calculate the molar mass of the enzyme.

Osmotic Pressure and Molar Mass

Please show and explain all work, including all parts of the formulas. Osmotic Pressure. What is the osmotic pressure (in mm Hg) of a solution at 25.0°C made by dissolving 0.0135 grams of tryptophan (C11H12N2O2) in enough water to give 75.0 mL of solution? Osmotic Pressure & Molar Mass. A 0.0116-gram sample of an unkno

% by weight of helium

Assume a mixture of radon and helium is separated by diffusion. What % by weight of the gases would be helium?

Mass Percent, atom percent, mass fraction, elemental fraction

To do any mass percent question one must first understand a little about fractions. If one has a fruit basket, with 3 apples, 2 oranges, 4 bananas, and a grapefruit, we could say that there is %30 apples in the basket, %20 oranges and so on if we were talking about the percentage by fruit. If we were talking about percenta

Mass Percent

What is the mass percent of a solution prepared by dissolving 18.9 grams of solid into 39.5 grams of water?

Reactions and Moles

How many moles of water are made from the reaction of 2.2 moles of oxygen gas with unlimited quantities of hydrogen gas? Given the reaction:2H2 + O2 > 2H2O

Volume Percentage

35.0 mL of gasoline in 200.0 mL of kerosene has what volume percentage?