All Chemistry Questions & Answers

Calculating molarity and molality.

A sample of potassium aluminum sulfate 12-hydrate, KAl(SO4)2.12H2O, containing 118.6 mg is dissolved in 1.000 L of solution. Calculate the following for the solution:

a. The molarity of KAl(SO4)2.

b. The molarity of (SO4)2

What does periodicity mean in chemistry?

What does it mean? how do i know waht it is? how do i find it? And can you please give a number of examples? thanx in advance!

Palladium crystal has 2 bond lengths, Alpha and Beta. How much energy does it take to go from alpha to beta?

A bond between two palladium can either be in the lowest engery state called alpha and a more excited state, called beta. How much energy does it take to go from alpha to beta? Or whats the difference in the bonds engery?


Enthalpy Question

2O3->3O2 deltaH=-285 kJ/molrxn 

Which reference electrode to select for electrochemical measurements? The one with Vycor or ceramic frit?
Is there any significant difference in quality and accuracy between reference electrode with Vycor frit (porous glass attached with heat-shrink tube) and the one 
equipped with ceramic frit (molten in the glass tube) like in this example
Percentage By Mass Calculation

A 4.675g sample of limestone (impure CaCO3) was treated with 375ml of 0.261 molL^-1 hydrochloric acid. After the reaction was over, the mixture was filtered and a 25 ml sample of the filtrate required 17.62ml of 0.0517 molL^-1 barium hydroxide solution for complete neutralisation. 

How do I find the initial energy of an electron given the wavelength and the final energy An electron jumps to the n = 4 level of a hydrogen atom after absorbing a photon of wavelength 1875 nm. What energy level did the electron move from? I haven't found equations for how to to find the energy absourbtion, just emission.
What is the percentage of cocaine in the mixture?

A sample of cocaine, C17H21O4N, is diluted with sugar, C12H22O11. When a 1.00 mg sample of this mixture is burned, 2.00 mg CO2 is formed. What is the percentage in this mixture?

Why are they dividing by 2 to find average?

Why are the dividing by 2 for the average rate? They should divide only when comparing, right? Where am I going wrong?

Can someone please explain and show me how to di this question please....

Jacy bought a gold necklace weighing 21.3 grams from the flea market. She filled a graduated cylinder with water to the 5.0mL mark and dropped her necklace in. The level in the  graduated cylinder rose to 704mL. is her necklace real or fake?