1. Which of the following is a precipitation reaction?
QUESTION:
Which of the following is a precipitation reaction?
A. Na2CO3(aq) + 2 AgNO3(aq)  Ag2CO3(s) + 2 NaNO3(aq)
B. 2 Mg(s) + O2(g)  2 MgO(s) C. HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
Precipitation: reaction in a liquid mixture formation of a solid product (insoluble in liquid)
Which of the following is a precipitation reaction?
A. Na2CO3(aq) + 2 AgNO3(aq)  Ag2CO3(s) + 2 NaNO3(aq)
2 Mg(s) + O2(g)  2 MgO(s)
Or C. HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
PAUSE
CLICK
A precipitation reaction occurs in liquid mixture and involves the formation of a solid product that is insoluble the liquid.
Therefore, we can eliminate choice C. This reaction does not have a solid product.
CROSS OUT Choice C
Both choices A and B have a solid product.
HIGHLIGHT Ag2CO3(s) and MgO(s)
But choice B does not involve a reaction in a liquid mixture.
SO choice B is wrong.
CROSS OUT Choice B.
The correct answer is choice A. Here, two aqueous solutions
HIGHLIGHT Na2CO3(aq) and AgNO3(aq)
… are mixed and a solid product…
HIGHLIGHT Ag2CO3(s)
… is formed.
The solid product is called a precipitate.
CALLOUT “Precipitate” pointing to Ag2CO3(s)
PAUSE END RECORDING

2. Video ID: © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08