1) Steel Wool Experiment
Before
Observations
After
Observations
Appearance
Steel wool dark gray,
Balloon deflated
Appearance
Steel wool dark
brown; Balloon
inflated
Mass (9)
485.68
Mass (9)
The students data can be seen here. A chemical reaction clearly took
place in the flask. One entry is missing: the mass of the system at the
end of the experiment. What amount should be added to the data
table?

Chemical reactions, chemistry, science as inquiry and data analysis. ... Students burn steel wool in both an open and closed environment to understand ... The difference in mass for this small sample of steel wool will be very small. ... careful attention to the balloon! 9. When rusting occurs the properties of the metal changes.

Explanation:

4.2 moles of sodium cyanide (NaCN) would be needed to produce  2.1 moles of sodium sulfate (Na₂SO₄).

Explanation:

The balanced reaction is:

H₂SO₄ + 2 NaCN → 2 HCN + Na₂SO₄

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound are necessary:

Then you can apply the following rule of three: if by stoichiometry to produce 1 mole of sodium sulfate 2 moles of sodium cyanide are necessary, then to produce 2.1 moles of sodium sulfate how many moles of sodium cyanide are necessary?

amount of moles of sodium cyanide= 4.2 moles

4.2 moles of sodium cyanide (NaCN) would be needed to produce  2.1 moles of sodium sulfate (Na₂SO₄).