Question

3a. text partially obscured, likely a math/science problem
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3b. tom is attempting to determine the density of a glass marble. he measures the mass of the marble to be 47.3 g. he also determined the volume to be 18.4 ml. calculate the density of the marble. (hint: mass/volume)
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3c. if an atom has 8 protons and a mass number of 14, how many neutrons does this atom have?
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3d. calculate the formula mass of magnesium phosphide, mg₃p₂.
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3e. what is the mass of 3.4 moles of silver, ag? (hint: convert moles to grams). the molar mass of silver is 107.87 g/mol.
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Explanation:

3C:

Step1: Recall the formula for mass number

Mass number ($A$) is the sum of protons ($p$) and neutrons ($n$), so $A = p + n$.

Step2: Solve for neutrons

We know $A = 14$ and $p = 8$. Rearranging the formula gives $n = A - p$. Substituting the values: $n = 14 - 8 = 6$.

Step1: Find atomic masses

Atomic mass of Mg: $24.305\ \text{g/mol}$, atomic mass of P: $30.974\ \text{g/mol}$.

Step2: Calculate formula mass

For $\ce{Mg3P2}$, formula mass = $3\times$ (atomic mass of Mg) + $2\times$ (atomic mass of P).
Formula mass = $3\times24.305 + 2\times30.974$
= $72.915 + 61.948$
= $134.863\ \text{g/mol}$.

Step1: Recall the formula for mass from moles

Mass ($m$) = moles ($n$) $\times$ molar mass ($M$).

Step2: Substitute values

Given $n = 3.4\ \text{mol}$, $M = 107.87\ \text{g/mol}$.
Mass = $3.4\ \text{mol} \times 107.87\ \text{g/mol}$
= $366.758\ \text{g}$.

Answer:

6

3D: