Answer:
When the solution (with phenolphthalein) changes to colorless
Explanation:
When titrating with HCl is common to add phenolphthalein as an acid-base indicator.
Phenolphthalein is pink or fucsia when added into a basic solution. On the other hand when it is in acid solutions, is colorless.
So, when titrating, the NaOH solution will be initialy pink due to the phenolphthalein and when reaching the equivalence point, that color will fade out into colorless. This is how you know you hace reached the equivalent point.
Answer:
Van der waal's force of attraction
Explanation:
Van der waal's force of attraction
Forces of Van der Waals involve attraction and repulsion among atoms, particles, and surfaces as well as many other intermolecular forces. These vary from covalent and ionic bonding in that they are caused by similarities in surrounding particle fluctuating polarizations (a result of quantum dynamics).
2-7 days, but depends on the procedure
Explanation:
When the student mixed the solution sodium carbonate with solution of copper(II) sulfate ; Copper Hydroxocarbonate , sodium sulfate and carbon dioxide gas was obtained as a products.
The balanced chemical reaction
Where:
= Copper(II) Hydroxocarbonate
= Sodium carbonate
= Copper(II) sulfate
= Sodium sulfate
= Carbon-dioxide
The student's test average is : 0.92
Total score obtained = 369
Number of tests = 4
Since Each test is exactly 100 points ;
The total score obtainable is (100 × 4) = 400
Average = score obtained / total score obtainable
Average = 369 / 400
Average = 0.9225
Average = 0.92
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