Question

Data Before Heating ---------- Mass beaker: 66.55 g Mass beaker + NaHCO3: 67.34 g Mass NaHCO3: 0.79 g After heating ---------- Mass beaker + residual solid (Na2CO3): 67.05 g Mass residual solid (Na2CO3): 0.5 g Calculate the mass (in grams) of the original sample that was lost as a gas upon heating. Calculate the mass-percent of the original sample that was lost upon heating. The original sample contained sodium bicarbonate (NaHCO3). Calculate the number of moles of the original sample, and the number of moles of each element in the original sample. NaHCO3: Na H C O Assuming all of the original sample decomposed, the remaining solid residue should be sodium carbonate (Na2CO3). Calculate the number of moles of the residue, and the number of moles of each element in the residue. Na2CO3: Na C O What is the ratio of moles of the original sample compound (before heating) compared to the moles of residue compound (after heating)? Express your answer as the nearest whole-number ratio (moles NaHCO3 : moles Na2CO3). What is the ratio of moles of each element in the original sample (before heating, see question 3) compared to moles of each element in the residue (after heating, see question 4)? In other words, compare Na before/after, C before/after and O before/after the reaction. (The sample shouldn't have any H left – that should have all escaped as a gas.)

          Data
Before Heating
----------
Mass beaker: 66.55 g
Mass beaker + NaHCO3: 67.34 g
Mass NaHCO3: 0.79 g

After heating
----------
Mass beaker + residual solid (Na2CO3): 67.05 g
Mass residual solid (Na2CO3): 0.5 g

Calculate the mass (in grams) of the original sample that was lost as a gas upon heating.
Calculate the mass-percent of the original sample that was lost upon heating.
The original sample contained sodium bicarbonate (NaHCO3). Calculate the number of moles of the original sample, and the number of moles of each element in the original sample.

NaHCO3:
Na
H
C
O

Assuming all of the original sample decomposed, the remaining solid residue should be sodium carbonate (Na2CO3). Calculate the number of moles of the residue, and the number of moles of each element in the residue.

Na2CO3:
Na
C
O

What is the ratio of moles of the original sample compound (before heating) compared to the moles of residue compound (after heating)? Express your answer as the nearest whole-number ratio (moles NaHCO3 : moles Na2CO3).

What is the ratio of moles of each element in the original sample (before heating, see question 3) compared to moles of each element in the residue (after heating, see question 4)? In other words, compare Na before/after, C before/after and O before/after the reaction. (The sample shouldn't have any H left – that should have all escaped as a gas.)

Added by Encarnacion M.

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