Arrhenius Acids and Bases

Question

A student in your class completed an acid/base lab but mixed up the labels on the chemicals. They tested NaOH, NaCl, and HCl. Use the data table below to determine the identity of each chemical. Write a scientific explanation on how you were able to classify each chemical. Be sure to include data from the lab along with scientific principles covered in this lesson.

Test Property | X | Y | Z |

______________|_________|_________|_________|

Litmus Paper | Turns red |Turns blue | No change| 

______________|_________|_________|__________|

pH   | 2  | 10 | 7 |

______________|________|_________|__________|_ 

Universal  |Turns red |Turns purple|Turns green|  

Indicator   | | | |

_________|_________|__________|_________| 

Reaction with 

Magnesium  |Reaction | No change |No change| 

_____________|__________|___________|________|

This is not the most organized chart but I hope you understand it

Answer 1

NaOH, NaCl, and HCl will all dissociate (separate into ions) in solution.

NaOH dissociates and forms OH^- (and Na⁺ but thats not important here). OH^- is a base, which means the NaOH solution would be expected to have a high pH.

NaCl will dissociate into Na⁺ and Cl^- and neither ion will effect the pH.

HCl will dissociate and form H⁺ ions (and Cl^- but thats not important). Anything that results in more H⁺ is an acid and would be expected to have a low pH.

If I am reading the table correctly...

X has a low pH = HCl

Y has a high pH = NaOH

Z has a neutral pH = NaCl