What Are the Correct Notations and Calculations in Basic Chemistry?

[konartist]

Hey guys I need some help on some chemistry questions (any help will help)

1. Is it more correct to write H+ (aq) or H3O+(aq)? Explain.
Now, as far as I know, these both mean the same thing, but we'd prefer to write H+ to help understand pH level right? I'm not too sure.

2. In words, what is the mass of 1 mole of any molecule?
The mass of one molecule is avagadros number right?

3. How many milliliters of 1.0 M HCL have to be added to neutralize 50 mL of 0.25 M NaOH?

I have not a clue where to start, if someone could tell me a formula, or get me started on this, I may be able to finish it.

Much thanks!

 

[geoffjb]

Hey guys I need some help on some chemistry questions (any help will help)

1. Is it more correct to write H+ (aq) or H3O+(aq)? Explain.
Now, as far as I know, these both mean the same thing, but we'd prefer to write H+ to help understand pH level right? I'm not too sure.

Typically, it comes down to context. Technically, $H^{+}$ becomes $H_{3}O^{+}$ in water.

2. In words, what is the mass of 1 mole of any molecule?
The mass of one molecule is avagadros number right?

No, Avagadro's number is the number of molecules/atoms/things in one mole of that molecule/atom/thing. The mass of one mole is the molar mass (try to convince yourself why).

3. How many milliliters of 1.0 M HCL have to be added to neutralize 50 mL of 0.25 M NaOH?

I have not a clue where to start, if someone could tell me a formula, or get me started on this, I may be able to finish it.

To start, write out the formula. Figure out the molar ratio (1:1, 2:1, 1:2, etc.), which is determined from the coefficients of the balanced formula. Then, determine how many moles you have of NaOH, and use the mole ratio to determine how many moles of HCl are needed to neutralize this. Finally, convert that amount (i.e. moles) into a volume. Watch your units throughout.

 

[Blueshift5]

1. It is more correct to write H3O+(aq) because it represents the hydrated form of the hydrogen ion in aqueous solution. H+ is often used as a shorthand notation, but it is technically not the most accurate representation of the ion in solution. H3O+ is a more accurate representation of the hydrated hydrogen ion.

2. The mass of one mole of any molecule is equal to its molar mass in grams. This is also known as Avogadro's number, which is approximately 6.022 x 10^23. This means that one mole of any molecule contains 6.022 x 10^23 individual particles.

3. To neutralize a solution, you need to add equal amounts of an acid and a base. In this case, you have 50 mL of 0.25 M NaOH, which means you have 0.25 moles of NaOH. To neutralize this, you would need to add an equal amount of HCl. The formula for calculating the amount of HCl needed is: (volume of NaOH) x (molarity of NaOH) = (volume of HCl) x (molarity of HCl). Plugging in the values, we get: (50 mL) x (0.25 M) = (volume of HCl) x (1.0 M). Solving for the volume of HCl, we get 12.5 mL. Therefore, you would need to add 12.5 mL of 1.0 M HCl to neutralize 50 mL of 0.25 M NaOH.