The Effect of Concentration on the Rate of a Chemical Reaction




This video shows a classic lab examining the effect of concentration of reactants on the rate of a chemical reaction.  This video supports NGSS HS-PS1-5.

In this experiment solutions of sodium thiosulfate and hydrochloric acid are combined in a beaker.  The reaction produces a precipitate which eventually makes the liquid turn cloudy.  The reaction beaker is placed over a piece of paper with a letter "X" printed on it.  The reaction is said to have gone to completion when the "X" can no longer be seen through the liquid in the beaker.

I have used this video as a warm up or as a flipped lesson which has students make observations, record data about the reaction time for the trials, create a graph and form a conclusion about the effect concentration has on the speed of a chemical reaction.

This lab was originally published by Flinn Scientific as a Chem Fax!  Use this link to see the full description of the experiment.

Comments

Post a Comment

Popular posts from this blog

HS-PS1-2: Trends of the Periodic Table

Image
HS-PS1-2:   Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties. This video covers important trends of the periodic table.  Topics include; reactivity, ionization energy, successive ionization energy, atomic radius, ionic radius, electron affinity, and electronegativity.
Read more

Oxidation of Magnesium - Empirical Formula

Image
This video summarizes an experiment performed to experimentally determine the empirical formula of magnesium oxide. In the lab the mass of a small sample of magnesium ribbon is measured. The metal is then heated in a crucible using a Bunsen burner to speed up the process of oxidation. The reaction forms the product magnesium oxide. The mass of this compound is measured and compared to the original amount of magnesium to determine the added mass of oxygen. The data collected allows students to calculate the empirical formula of the magnesium oxide compound. The reaction is summarized by the following chemical equation. 2Mg  +  O 2  →  2MgO The compound forms with a 1:1 ratio of magnesium to oxygen. This is because magnesium has two valence electrons which are donated to the oxygen atoms. The oxygen atoms can add two electrons to complete their valence shell. I hope this was helpful.
Read more

HS-PS4-5: Communicate technical information about devices that transmit and capture information and energy.

Image
HS-PS4-5. Communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy.* [Clarification Statement: Examples could include solar cells capturing light and converting it to electricity; medical imaging; and communications technology.] HS-PS4-5. Evidence Statements This performance expectation has students communicating technical information about two devices using varying formats (textual,  graphical, oral and mathematical are listed in NGSS evidence statements.  I'm having my students research two devices (one that relies on the photoelectric effect, a second that depends on wave properties) and then create a screencast video using text, images and narration to teach their classmates about the device they selected. Devices that depend on the Photoelectric Effect: Photovoltaic cells (solar panels) Photocopiers Charge coupled devi
Read more