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The first step to determine the amount of bromine in seawater involves calculating the total mass of the seawater. You start by knowing the volume of seawater given in liters. In this problem, it's 2.50 liters. To work effectively with density, we need the volume in cubic centimeters. Remember, 1 liter is equivalent to 1000 cubic centimeters.
To convert 2.50 liters to cubic centimeters:

• 2.50 liters x 1000 cm³/liter = 2500 cm³

Next, we use the formula for density. Density is defined as mass per unit volume, often written as:
\[\text{Density} = \frac{\text{Mass}}{\text{Volume}}\]If you rearrange the formula to solve for mass, it becomes:
\[\text{Mass} = \text{Density} \times \text{Volume}\]Here, the density of seawater is 1.025 g/cm³. Now, multiply the density by the volume to find the mass of the seawater:

• Mass = 1.025 g/cm³ x 2500 cm³ = 2562.5 g

Once you have figured out the total mass of the seawater, the next step is to calculate the mass of bromine contained within that seawater. The problem states that bromine comprises 0.0065% of the seawater by mass.
This kind of percentage is called 'mass percent'. It tells you how many grams of a substance, in this case bromine, are present in 100 grams of the solution or mixture.
Using mass percent is straightforward. To find how much bromine is in 2562.5 grams of seawater, apply the formula:

• \[\text{Mass of bromine} = \left(\frac{\text{Percentage}}{100}\right) \times \text{Total mass of seawater}\]
• \[\text{Mass of bromine} = \left(\frac{0.0065}{100}\right) \times 2562.5\]
• This results in approximately 0.1665625 grams of bromine in the seawater.

To conclude, we calculate the mass of bromine present in the given seawater. Given that we've derived bromine's mass percentage and the total mass of seawater, you might ask: why is this calculation useful?
Although the percentage is quite small (0.0065%), it's crucial for chemical engineers and environmental scientists to precisely understand these concentrations for various applications, such as desalination or chemical extraction processes.
In practical terms, we treat bromine as any other solute in a solvent. Bromine's low concentration might make detection and calculation seem trivial, but accurate measurements ensure effective chemical management and utilization.
Take note:

• Always keep track of unit conversions to avoid inconsistencies.
• Double-check calculations to ensure accuracy, especially with smaller percentages.

Through these calculated steps, we can determine the specific amount of a solute, such as bromine, in a given volume of solvent, like seawater.