Chemistry (including Biochemistry)/Chemistry

Advertisement


Question
You are given 1.448 g of brass and are told to assume that the brass is 100% Copper. Could you show how to calculate the mL of nitric acid needed to completely react with the brass? Thank you!

Answer
First order of business is to balance the chemical equation

Cu (s) + HNO3 (aq) --> Cu(NO3)2 (aq) + NO2 (g) + H20 (l)

Once balanced, calculate the number of moles of Cu you have using

mass Cu / atomic weight of Cu = moles of Cu

Once you know the number of moles of Cu, use your balanced equation to figure out how many moles of HNO3 you need to react all of it

moles of Cu * (n number of moles of HNO3/ m number of moles of Cu) = moles of HNO3 needed
where n is the molar coefficient for HNO3 and m is the molar coefficient for Cu in the balanced equation

Since you are asked for mL of nitric acid, you need to know the concentration... which you have not provided. Find that. Then find out how much you need.

moles of HNO3 needed / molar concentration of your HNO3 solution = volume of HNO3 solution needed.

Note that if you are assuming a concentrated solution of HNO3, that is a value you can just look up online (like in this table https://www.erowid.org/archive/rhodium/chemistry/equipment/molarity.html)

I hope this helps!

Chemistry (including Biochemistry)

All Answers


Answers by Expert:


Ask Experts

Volunteer


Dr. Jeffery Raymond

Expertise

Materials chemistry. Materials science. Spectroscopy. Polymer science. Physical Chemistry. General Physics. Technical writing. General Applied Mathematics. Nanomaterials. Optoelectronic Behavior. Science Policy.

Experience

Teaching: General Inorganic Chemistry I & II, Organic Chemistry I & II, Physical Chemistry I, Polymeric Materials, General Physics I, Calculus I & II
My prior experience includes the United States Army and three years as a development chemist in industry. Currently I am the Assistant Director of the Laboratory for Synthetic Biological Interactions. All told, 13 years of experience in research, development and science education.

Organizations
Texas A&M University, American Chemical Society, POLY-ACS, SPIE

Publications
Journal of the American Chemical Society, Nanoletters, Journal of Physical Chemistry C, Journal of Physical Chemistry Letters, Ultramicroscopy Proceedings of SPIE, Proceedings of MRS, Polymer News, Chemical and Engineering News, Nano Letters, Small, Chemistry.org, Angewandte

Education/Credentials
PhD Macromolecular Science and Engineering (Photophysics/Nanomaterials Concentration), MS Materials Science, BS Chemistry and Physics, Graduate Certificate in Science Policy, AAS Chemical Technology, AAS Engineering Technology

©2016 About.com. All rights reserved.