Entropy for reaction

Calculate "delta" S for the following reaction: H2(g) + Br2(l) --> 2HBr(g) given: S[H2(g)] = 0.131 kJ/K S[Br2(l)] = 0.152 kJ/K S[HBr(g)] = 0.199kJ/K a. 0.482 kJ/K b. 0.681 kJ/K c. 0.115 kJ/K d. -0.084 kJ/K e. 0.084 kJ/K

Rate equation

For the second order reaction below, the concentration of A after 125 seconds is 0.0722M. If k=9.11x10(exponent negative 2) seconds(exponent negative 1), what ws the initial concentration of A? 2A-->B

Finding molarity and answering questions on 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/mol)?

Rate of radioactive decay-half life

How many atoms decay in 24 hours in a 2.5 x 10(exponent negative 6) Ci source? 1 Ci=3.700 x 10(exponent 10) atom/s. Please show how you arrive at the solution. thanks a. 0.22 atoms b. 1.3 x 10(exponent 21) atoms c. 9.3 x 10(exponent 4) atoms d. 2.3 x 10(exponent 6) atoms e. 8.0 x 10(exponent 9) atoms

Half life

A 1.00g of sample of Ge decays to 0.87 in 1.9hr. What is the half-life of Ge? Please show how you arrive at the solution. thanks a. 1.4 x 10(exponent 1)hr b. 9.5 hr c. 1.1 x 10(exponent negative 1) hr d. 7.3 x 10(exponent negative 2) hr e. 13 hr