General Chemistry Answers

how to calculate molar concentration

What mass of oxygen gas is needed to burn 44.6 g of propane (C 3 H 8 (g) in a complete combustion reaction ?

A 0.2719g sample containing (blank)3 reacted with 20.00mL of 0.2254 M HCl. Given that HCl was excess. The excess HCl required exactly 20.00mL of 0.1041 M NaOH to reach the end-point using phenolphthalein indicator. Determine percentage purity of (blank)3 in the sample.

The reaction involved is

3( )+2 ( )→ 2( )+2 2O(l)

The titration reaction is

( )+NaOH(aq) Cl( )+ 2 (l)

Devise a procedure for selectively precipitating the following ions from each other in a common solution. Record your table, the order the solutions must be added and the precipitate that forms at each step. (4 each)

a. Cl- and PO4 3-

b. Ca2+ and Ag+

c. Cu2+ and Ca2+

Calculate the molarity of a solution prepared by dissolving 250.0 g of Ca(NO₃)₂ in enough water to make 3.50 L of solution.

 a

5.34 M

 b

0.45 M

 c

1.52 M

 d

71.4 M

a sample of a gas taken at STP was analyzed and found to have a volume of 6.3L.The gas was taken place to a chamber where the pressure is increased by 50% while decreasing the temperature by 25% with respect to its original condition. calculate the volume increase/decrease of the gas

Which of the following assertions are CORRECT? (i) HCl(g) is not an Arrhenius acid but HCl(aq) is. (ii) NH3 is a Bronsted and Lowry base as well as Lewis base. (iii) H2O(l) can be a Bronsted and Lowry base but never a Bronsted and Lowry acid. (iv) Electron deficient molecules are Lewis acids.

On analysis a 0.500 g sample of aluminium chloride is found to contain 0.101 g of aluminium. Determine the emperical formula of aluminium chloride

Reaction between solid phosphorous, P4 and oxygen gas, produces P3O6 and 1640.1kJ of heat.

The decomposition of Nitrogen dioxide into Nitric oxide and oxygen is an example

of a second-order reaction. It has a rate constant of 0.54 M-1s-1 at 300 Celsius.

(a) If the initial concentration of NO2 is 0.00800 M, what is the concentration of NO2 after

20.0 minutes? 

(b) If the initial concentration of NO2 is 0.00800 M, what is the half-life?