Easy Medal

Cindy hypothesizes that if she adds salt to a weak acid, then its pH will be lowered. She develops the following experiment to test her hypothesis. Which of the following steps could compromise the validity of her experiment?

Fill two beakers with 50 mL of the same weak acid.
Add salt to the first beaker.
Add water to the second beaker.
Measure the pH of the solution in each beaker.

step 2
step 1
step 4
step 3

Question

Easy Medal


Cindy hypothesizes that if she adds salt to a weak acid, then its pH will be lowered. She develops the following experiment to test her hypothesis. Which of the following steps could compromise the validity of her experiment?

    Fill two beakers with 50 mL of the same weak acid.
    Add salt to the first beaker.
    Add water to the second beaker.
    Measure the pH of the solution in each beaker.

    step 2
    step 1
    step 4
    step 3

anonymous · Answer

I think what they're getting at is there is no control

anonymous · Answer

It would be step 3. If she put the acid in, put the salt in the first beaker, and then measured the ph in each beaker, that would confirm if it lowered because it would be comparing the plain acid to the acid with the salt.  If she added water to the second beaker, it would change the acid, and then her experiment wouldn't turn out correctly.

anonymous · Answer

@SACAPUNTAS that makes sense to you, too, right?

anonymous · Answer

correct tht would be the answer

anonymous · Answer

Yes. I didn't want to type all that because I am lazy but I agree with it. :D