Other Chemistry Answers

The half-life of strontium-91, 91

38Sr is 9.70 h. Find

(a) its decay constant, and (5pts)

(b) for an initial 1.00-g sample, the activity after 15 hours.

5.00 g of sodium hydroxide is dissolved in 150 mL of water. Using a coffee-cup calorimeter, the temperature change of the water is measured to be 2.2 degrees celsius. The specific heat capacity of water is 4.184 J/g°C. Calculate the heat released per gram of sodium hydroxide dissolved.

for CH4(g) + 3Cl2(g) ——> CHCl3(g) + 3HCl(g) how many grams of CH4 is needed to produce 45.5 g CHCl3

the reaction of finely divided aluminum and iron(III) oxide, Fe2O3, is called the thermite reaction. it produces a tremendous amount of heat, making the welding od railroad track possible. the reaction of 500.0 grams of aluminum and 500.0 grams of iron(iii) oxide produces 166.5 grams iron. calculate the mass of iron that should be released by this reaction.

1. We are given the initial pressure of 1.5 atm and temperature of 25⁰C of the gas and asked for the pressure at a higher temperature of 450⁰C 

A tank contains 78.0 g of N₂ and 42.0 g of Ne at a total pressure of 3.75 atm and a temperature of 50.0°C. Calculate the following quantities.

(a) moles of N₂

(b) moles of Ne

(c) the partial pressure of N₂

(d) the partial pressure of Ne

Given the following amounts of gases calculate the number of moles of each gas. Calculate the volume each amount of gas would occupy at 100°C and 15 atm.

a. 5.8g NH₃

b. 48g O₂

In an experiment of titration, 25.0 mL of potassium hydroxide solution is poured

into a conical flask. A few drops of phenolphthalein are added into the solution.

The solution in the conical flask is titrated with 1.0 M sulphuric acid.

a)What is the function of phenolphthalein in this experiment

b)Write a balanced chemical equation for the reaction.

c) In this experiment, 20.00 mL sulphuric acid needed to react with 25.0 

mL of potassium hydroxide.

i. Calculate the mole for sulphuric acid.

ii. Calculate the molarity of potassium hydroxide solution.