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Question7. Which neutralizes 4 mol4 \mathrm{~mol} of NaOH\mathrm{NaOH}: a. 2 mol2 \mathrm{~mol} of HBr\mathrm{HBr} b. 2 mol2 \mathrm{~mol} of H2CrO4\mathrm{H}_{2} \mathrm{CrO}_{4} c. 2 mol2 \mathrm{~mol} of H3PO4\mathrm{H}_{3} \mathrm{PO}_{4} d. 2 mol2 \mathrm{~mol} of HF?
8. Best pH\mathrm{pH} indicator for acetic acid CH3COOH\mathrm{CH}_{3} \mathrm{COOH} with NaOH\mathrm{NaOH}: a. methyl orange b. methyl red c. bromthymol blue d. phenolphthalein?
9. Lowest pOH\mathrm{pOH}: a. 0.1MNaNO30.1 \mathrm{M} \mathrm{NaNO}_{3} b. 1MNaNO31 \mathrm{M} \mathrm{NaNO}_{3} c. 2MNaNO22 \mathrm{M} \mathrm{NaNO}_{2} d. (a) and (b)?
10. True for acidic solution at all temps: a. [H3O+]>[OH−]\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]>\left[\mathrm{OH}^{-}\right] b. [H3O+]>1×10−7M\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]>1 \times 10^{-7} \mathrm{M} c. [OH−]<1×10−7M\left[\mathrm{OH}^{-}\right]<1 \times 10^{-7} \mathrm{M} d. all are true?

Studdy Solution

STEP 1

Assumptions1. We are assuming that the reaction between NaOH and the other compounds is a neutralization reaction, which means that the NaOH reacts with the H+ ions in the other compounds to form water and a salt. . We are assuming that the reaction goes to completion, meaning all of the NaOH and the other compound react completely.
3. We are assuming that the molar ratios in the balanced chemical equations for these reactions tell us how many moles of NaOH are needed to neutralize a given number of moles of the other compound.

STEP 2

First, let's write out the balanced chemical equations for the reactions between NaOH and the other compounds.For HBrNaOH+HBr→NaBr+H2\mathrm{NaOH} + \mathrm{HBr} \rightarrow \mathrm{NaBr} + \mathrm{H}_{2}\mathrm{}For H2Cr42NaOH+H2Cr4→Na2Cr4+2H22\mathrm{NaOH} + \mathrm{H}_{2}\mathrm{Cr}_{4} \rightarrow \mathrm{Na}_{2}\mathrm{Cr}_{4} +2\mathrm{H}_{2}\mathrm{}For HPO4NaOH+HPO4→NaPO4+H2\mathrm{NaOH} + \mathrm{H}_{}\mathrm{PO}_{4} \rightarrow \mathrm{Na}_{}\mathrm{PO}_{4} +\mathrm{H}_{2}\mathrm{}For HFNaOH+HF→Na+H2\mathrm{NaOH} + \mathrm{HF} \rightarrow \mathrm{Na} + \mathrm{H}_{2}\mathrm{}

STEP 3

From the balanced chemical equations, we can see that1 mol of NaOH is needed to neutralize1 mol of HBr or HF,2 mol of NaOH are needed to neutralize1 mol of H2Cr, and3 mol of NaOH are needed to neutralize1 mol of H3PO.

STEP 4

Given that we have4 mol of NaOH, we can neutralize4 mol of HBr or HF,2 mol of H2Cr4, or1.33 mol of H3PO4.

STEP 5

Comparing these amounts with the given amounts of the other compounds, we see that4 mol of NaOH can neutralize2 mol of HBr (option a),2 mol of H2Cr4 (option b), but not2 mol of H3PO4 (option c) or2 mol of HF (option d).
Therefore, the answer is options a and b.
For questions8,9, and10, similar steps can be followed, but the specific steps will depend on the details of the questions. For example, for question8, one would need to consider the pH at the equivalence point of the titration and the pH range over which the different indicators change color. For question9, one would need to calculate the pOH of the different solutions. For question10, one would need to consider the definitions of acidic solutions and the concentrations of H3+ and OH- in such solutions.

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