What mass of chromium is found in a 13.28 g sample of Na_(2)CrO_(4) a 3.39 g Cr b 4.97g Cr C 1.90 g Cr d 4.26 g Cr

To determine the mass of chromium in a 13.28 g sample of \( Na_2CrO_4 \), we need to follow these steps:<br /><br />1. Calculate the molar mass of \( Na_2CrO_4 \).<br />2. Determine the number of moles of \( Na_2CrO_4 \) in the sample.<br />3. Calculate the mass of chromium in the sample.<br /><br />### Step 1: Calculate the Molar Mass of \( Na_2CrO_4 \)<br /><br />- Sodium (Na): 22.99 g/mol<br />- Chromium (Cr): 51.996 g/mol<br />- Oxygen (O): 16.00 g/mol<br /><br />\[ \text{Molar mass of } Na_2CrO_4 = 2 \times 22.99 + 51.996 + 4 \times 16.00 \]<br />\[ = 45.98 + 51.996 + 64.00 \]<br />\[ = 161.976 \text{ g/mol} \]<br /><br />### Step 2: Determine the Number of Moles of \( Na_2CrO_4 \) in the Sample<br /><br />\[ \text{Number of moles} = \frac{\text{mass}}{\text{molar mass}} \]<br />\[ = \frac{13.28 \text{ g}}{161.976 \text{ g/mol}} \]<br />\[ \approx 0.082 \text{ moles} \]<br /><br />### Step 3: Calculate the Mass of Chromium in the Sample<br /><br />Each mole of \( Na_2CrO_4 \) contains 1 mole of chromium. Therefore, the number of moles of chromium is also 0.082 moles.<br /><br />\[ \text{Mass of Cr} = \text{number of moles} \times \text{molar mass of Cr} \]<br />\[ = 0.082 \text{ moles} \times 51.996 \text{ g/mol} \]<br />\[ \approx 4.27 \text{ g} \]<br /><br />Therefore, the mass of chromium in the 13.28 g sample of \( Na_2CrO_4 \) is approximately 4.27 g.<br /><br />The closest answer to this calculation is:<br />d) 4.26 g Cr