ACT Red book Science Section *HELP*

Test Preparation ACT Preparation
1

<p>For number 31 in the Science section of practice test 3, it says : "In trial 1 of Experiment 1, after the reaction had taken place, but before the syringe plunger was unlocked, one would predict that, compared to the pressure in the syringe before the spark, the pressure in the syringe after the spark was: a) lower, because the overall amount of gas decreased, b) lower, because the overall amount of gas increased, c) higher, because the overall amount of gas decreased, d) higher, because the overall amount of gas increased.</p>

<p>I knew that the overall amount(volume) of gas decreased from the data given in the Table provided.
At first I put A (which is the correct answer), but then I remembered P1V1=P2V2, that as pressure increases, the volume decreases. So instead, I changed my answer to C, so I got it wrong. </p>

<p>Any explanation on why the decrease in the overall amount of gas in the syringe which led to a decrease in the volume of the contents of the syringe decreased the pressure in the syringe?</p>

2

<p>Forgive me if I’m wrong, but doesn’t the rule apply to the volume of the container? Logically, as the container gets smaller, the available volume decreases and as a result, the gases inside bounce against the walls more frequently–increasing pressure. </p>

<p>However in this case, the volume of the container stays the same, and the quantity of gas decreases, therefore, less gas molecules bouncing around and thus, less pressure-- was my way of looking at it.</p>