find [H3O+] and [OH-]

1)a solution that is 5.8×10−2 M in [HBr] and 1.9×10−2M in [NO3].

2)a solution that is 0.780% HNO3 by mass (Assume a density of 1.01 g/mL for the solution.)

(H^+) HBr soln = (HBr)

To find OH, remember (H^+)(OH^-) = Kw = 1E-14

0.780% by mass means 0.78g/100 g soln.
Use density to convert 100 g soln to mL. Convert 0.78 g to mols. That will give you molarity and you can go from there.

To find [H3O+] and [OH-] in the given solutions, we need to make some assumptions and use the concept of acid-base reactions. We will assume that all HBr and HNO3 molecules dissociate completely in water.

1) The reaction between HBr and H2O can be represented as follows:

HBr (aq) + H2O (l) -> H3O+ (aq) + Br- (aq)

Since HBr is a strong acid, it completely dissociates in water. Therefore, the concentration of H3O+ in the solution is equal to the concentration of HBr, which is given as 5.8×10−2 M.

2) The reaction between HNO3 and H2O can be represented as follows:

HNO3 (aq) + H2O (l) -> H3O+ (aq) + NO3- (aq)

Similarly, since HNO3 is a strong acid, it completely dissociates in water. We are given the percentage mass of HNO3 in the solution, and the density of the solution, which allows us to calculate the concentration of HNO3.

First, we need to calculate the mass of HNO3 in the solution.
Mass of HNO3 = 0.780% × Mass of solution

Next, we can calculate the moles of HNO3 using its molar mass (63.01 g/mol).
Moles of HNO3 = Mass of HNO3 / Molar mass of HNO3

Finally, we can calculate the concentration of HNO3 in the solution using its volume (density × mass of solution) in liters.
Concentration of HNO3 = Moles of HNO3 / Volume of solution

Now that we have the concentration of HNO3, we can conclude that the concentration of H3O+ is also equal to it.

To find [H3O+] and [OH-] for the given solutions, we need to understand the concept of pH and pOH. pH is a measure of the concentration of hydronium ions ([H3O+]) in a solution, while pOH is a measure of the concentration of hydroxide ions ([OH-]) in a solution. The relationship between pH and pOH is given by the equation:

pH + pOH = 14

Let's calculate [H3O+] and [OH-] for each solution:

1) Solution 1 - 5.8×10−2 M in HBr and 1.9×10−2 M in NO3:

[HBr] dissociates to form H+ and Br- ions, while [NO3] dissociates to form NO- and OH- ions. However, because HBr is a strong acid and NO3 is a polyatomic ion without basic character, we can assume that H+ ions come only from HBr.

Since HBr is a strong acid, we can assume that all of it dissociates. Therefore, the concentration of [H3O+] is equal to the concentration of the HBr solution, which is 5.8×10−2 M.

To find the concentration of [OH-], we need to determine the concentration of OH- ions from the NO3 solution. However, NO3 does not have basic character, so it does not provide any OH- ions. Therefore, the concentration of [OH-] in this solution is 0.

2) Solution 2 - 0.780% HNO3 by mass (Assume a density of 1.01 g/mL for the solution):

First, we need to convert the percentage by mass to grams. Assuming we have 100g of the solution, 0.780g will be HNO3.

Next, we calculate the number of moles of HNO3 using its molar mass. The molar mass of HNO3 is 1 + 14 + 3(16) = 63 g/mol.

Number of moles of HNO3 = mass of HNO3 / molar mass
= 0.780g / 63 g/mol ≈ 0.0124 mol

Since HNO3 is a strong acid, it dissociates completely to form H+ and NO3- ions. Therefore, the concentration of [H3O+] is equal to the number of moles of HNO3, which is 0.0124 M.

To find the concentration of [OH-], we need to use the equation: [H3O+] × [OH-] = 10^-14 (at 25°C).

Therefore, [OH-] = 10^-14 / [H3O+]
= 10^-14 / 0.0124
≈ 8.06 × 10^-13 M

So, for solution 2, the concentration of [H3O+] is 0.0124 M and the concentration of [OH-] is 8.06 × 10^-13 M.

In summary:
1) Solution 1: [H3O+] = 5.8×10−2 M, [OH-] = 0
2) Solution 2: [H3O+] = 0.0124 M, [OH-] = 8.06 × 10^-13 M