Chemistry Answers

Titration of 0.2121 g of pure Na2C2O4 (134.00 g/mol) required 43.31 mL

of KMnO4.What is the molar concentration of the KMnO4 solution?

Titration of 0.2121 g of pure Na2C2O4 (134.00 g/mol) required 43.31 mL

of KMnO4.What is the molar concentration of the KMnO4 solution? The

chemical reaction is

2MnO4 + 5C2O4+ 16H* ->2Mn+ 10CO2+ 8H2O

Helium gas is contained inside a piston cylinder assembly as shown in the figure. Initially the gas is

having pressure 1 bar and volume 0.01 m3

. Then the current is supplied, and the gas is heated such

that the final pressure is 1.2 bar and the final volume is 0.0145 m3

. 10 % of the electrical energy

supplied to the gas is lost as heat from the cylinder. Determine the followings. If necessary, make

assumption(s) with justification.

(a) How long the current is supplied if process is ideal?

(b) How long the current is supplied if process is real?

describe the preparation of 900 ml of 3 M HNO3 from the commercial reagent that is 70.5% HNO3 (w/w) and has a specific gravity of 1.42

Use the localised electron model to describe the bonding in hydrogen cyanide and phosgene( COCL2)

For each of the following molecules, write the Lewis structure(s), predict the molecular structure (including bond angles), give expected hybrid orbitals on the central atom, and predict the overall polarity. a. OF2 b. AsF5 c. IF5

Steel wool , which is made of pure iron metal, burns with oxygen gas to produce ferric oxide (Fe2O3). Fe(s) + O2(g) ( Fe2O3

If there are 1.25 moles of Fe and 1.25 moles of O2,

How many moles of Fe2O3 will be produced? What is its mass?

If the actual laboratory yield is 95.8g Fe2O3, what is the rection’s percent yield?

Pure aluminum (Al) metal reacts with hydrocholoric acid (HCl) to produce aluminum chloride (AlCl3) and hydrogen (H2) gas.

Write the balanced chemical equation for the reaction described above.

If the expected mass of AlCl3 to be formed is 3.5g, what should be the initial mass of the pure aluminum metal?

If the actual mass of AlCl3 produced is 3.1g, what is the percentage yield of the reaction?

How many moles of O2 will be formed if 5.0 moles of H2O decomposed into H2 and O2?

Chemical Equation: H2O ( H2 + O2

How many moles of O2 are needed to burn 100 g of propane (C3H8)?

Chemcial Equation: C3H8 + O2 ( CO2 + H2O

If 50.0 grams of Cl2 gas is reacted with enough sodium hydroxide (NaOH), calculate the following:

Mass in grams of sodium hypochlorite (NaOCL) produced

Moles of sodium chloride (NaCl) produced

Chemical Equation: NaOH + Cl2 ( NaOCl + NaCl + H2O

2. A solution containing 0.402 49 g of CoCl2 ∙ xH2O (a solid with an unknown number of waters of hydration) was exhaustively electrolyzed to deposit 0.09937 g of metallic cobalt on a platinum cathode by the reaction Co2+ + 2e-  Co(s). Calculate the number of moles of water per mole of cobalt in the reagent.

The standard enthalpy of formation, ΔH˚f of liquid ethanol, C2H5OH(l) @ 25C is -277.63 kJ/mol.  Calculate its heat of combustion at constant pressure from the given reaction, C2H5OH(l)+ 3 O2(g) → 2 CO2(g) + 3 H2O(l). ΔH˚f CO2=-393.50 kJ/mol ΔH˚fH2O= -285.84 kJ/mol