How many bromide ions are present in 65.5 mL of 0.210 M GaBr 3 solution?

Here in this practice question it says, how many bromide ions are present in 65.5 milli liters of 0.210 molar Gallium Bromide solution. Again, we've said this in the past. When two numbers are connected by the word of, it means multiply. And realize that moles equals liters times molarity. So I'm gonna start off by converting these milliliters into liters. So 1 milli is 10 to the negative 3 liters and molarity is moles per liter. So this is equal to point 210 moles of Gallium Bromide over 1 liter. Now that I have moles of gallium bromide, remember I'm looking for bromide ions, I can say that one mole of my entire compound has within it, we see 3 moles of bromide ions. Now at this point, they're asking me for bromide ions. They're not asking me for moles of bromide ions. If they were asking me for moles of bromide ions, I would just stop here. Instead, they just say they want ions. Remember, we use the term ions when we have a single element with a charge. And remember, to go from moles to ions, we have to use Avogadro's number. So we're gonna say here 1 mole of bromide ions is 6.022 times 10 to the 23 bromide ions. Because here we have a number times 10 to a power, make sure you place it in parenthesis. If you do this correctly, you get at the end 2 point 48 times 10 to the 22 bromide ions as your final answer. So just remember, ions not moles of ions in this case means that we have to go one step further and utilize Avogadro's number to isolate our final answer.

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9. Solutions

Osmolarity

GOB Chemistry

9. Solutions

Osmolarity

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Multiple Choice

How many bromide ions are present in 65.5 mL of 0.210 M GaBr₃solution?

7.95x10²² ions

2.48x10²² ions

7.95x10²³ ions

6.50x10²³ ions

3.91x10²³ ions

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Verified step by step guidance

First, understand that the molarity (M) of a solution is defined as the number of moles of solute per liter of solution. Here, you have a 0.210 M solution of GaBr3, which means there are 0.210 moles of GaBr3 in 1 liter of solution.

Convert the volume of the solution from milliliters to liters. Since there are 1000 milliliters in a liter, divide 65.5 mL by 1000 to get the volume in liters.

Calculate the number of moles of GaBr3 in the given volume of solution using the formula: \( \text{moles of GaBr3} = \text{molarity} \times \text{volume in liters} \).

Recognize that each formula unit of GaBr3 dissociates into one Ga^3+ ion and three Br^- ions in solution. Therefore, the number of moles of Br^- ions is three times the number of moles of GaBr3.

Finally, convert the moles of Br^- ions to the number of ions using Avogadro's number, which is \( 6.022 \times 10^{23} \) ions/mole. Multiply the moles of Br^- ions by Avogadro's number to find the total number of bromide ions.