When 280. mL of 1.50 x 10-4 M hydrochloric acid is added to 135 mL of 1.75 x 10-4 M Mg(OH)2, the resulting solution will be:
acidic.
basic
neutral.
It is impossible to tell from the information given.
To determine the resulting solution, we need to compare the concentration of H+ ions (from the HCl) and OH- ions (from the Mg(OH)2).
Balanced equation for the reaction between HCl and Mg(OH)2 is:
2HCl + Mg(OH)2 -> MgCl2 + 2H2O
From the equation, we can see that HCl is an acid (it donates H+ ions), while Mg(OH)2 is a base (it produces OH- ions).
To find the total concentration of H+ ions, we multiply the initial concentration of the HCl by its volume and divide by the final volume:
Total H+ = (Initial HCl concentration) * (Initial HCl volume) / (Final volume)
= (1.50 x 10^-4 M) * (280 mL) / (280 mL + 135 mL)
= (1.50 x 10^-4 M) * (280 mL / 415 mL)
= (1.50 x 10^-4 M) * (0.675)
≈ 1.01 x 10^-4 M
To find the total concentration of OH- ions, we multiply the initial concentration of the Mg(OH)2 by its volume and divide by the final volume:
Total OH- = (Initial Mg(OH)2 concentration) * (Initial Mg(OH)2 volume) / (Final volume)
= (1.75 x 10^-4 M) * (135 mL) / (280 mL + 135 mL)
= (1.75 x 10^-4 M) * (135 mL / 415 mL)
= (1.75 x 10^-4 M) * (0.325)
≈ 5.69 x 10^-5 M
Since the concentration of H+ ions is greater than the concentration of OH- ions, the resulting solution will be acidic.
Therefore, the answer is acidic.
To determine whether the resulting solution will be acidic, basic, or neutral, we need to compare the acidic and basic properties of the substances involved.
Hydrochloric acid (HCl) is a strong acid that dissociates completely in water, meaning it releases all its H+ ions into solution. This results in an increase in the concentration of H+ ions and the solution becomes acidic.
On the other hand, magnesium hydroxide (Mg(OH)2) is a strong base that dissociates completely in water, releasing hydroxide ions (OH-). This leads to an increase in the concentration of OH- ions and makes the solution basic.
When an acid and a base react, they undergo a neutralization reaction. The H+ ions from the acid combine with the OH- ions from the base to form water, thereby reducing the concentrations of both ions and resulting in a neutral solution.
In this scenario, we have hydrochloric acid reacting with magnesium hydroxide. However, we need to determine which substance is present in excess. To do this, we can compare their initial concentrations and volumes.
The initial concentration of hydrochloric acid is 1.50 x 10-4 M, and the volume is 280 mL. Therefore, the initial amount of hydrochloric acid is:
0.000150 M x 0.280 L = 0.000042 moles
Similarly, the initial concentration of magnesium hydroxide is 1.75 x 10-4 M, and the volume is 135 mL. The initial amount of magnesium hydroxide is:
0.000175 M x 0.135 L = 0.000024 moles
Comparing the amounts of acid and base, we see that there are more moles of hydrochloric acid than magnesium hydroxide. This means the hydrochloric acid is present in excess.
Therefore, when the hydrochloric acid reacts with the magnesium hydroxide, all the hydroxide ions will be consumed to form water. However, some H+ ions will remain in the solution, making it acidic.
Therefore, the resulting solution will be acidic.
Write the equation and balance it.
moles HCl = M x L
moles Mg(OH)2 = M x L
Determine which is the limiting reagent and that will determine that the OTHER reagent will be the one in excess. Go from there.