9 g of hydrogen - 42 g of nitrogen
5 g of hydrogen - x g of nitrogen
The mass of nitrogen in the second sample is 23.33 g.
Answer : Option B) The molecules in the thermometer’s liquid spread apart.
Explanation : When a thermometer was placed in water to measure the water’s temperature. the molecules in the thermometer liquid which is often mercury spreads apart and rises, this shows a temperature increase in the thermometer.
The key to most "how do I separate." questions is solubility.
The trick is to add a liquid that will only dissolve one substance but not another.
Let's say you had a beaker full of sand, table salt (NaCl), and acetanilide. Is there anything you can add that would only dissolve one of these three substances?
Yes, there is! Acetanilide like most organic compounds, isn't soluble in water. But salt is soluble in water. So to the mixture, I would add water, and then pass the water through a filter. The filter paper will "catch" the sand and acetanilide, but the table salt will remain dissolved in the water. If you then let that water evaporate (either via boiling or under vacuum), you will recover your salt.
So now, how to do you separate the sand from the acetanilide? Sand isn't really soluble in anything, but acetanilide is soluble in organic solvents, such as ethanol. So to the mixture of sand and acetanilide, add ethanol, and pass it through a filter. The sand will once again get stuck in the filter paper, and your acetanilide will be dissolved in ethanol. Remove the ethanol (via vacuum, or rotovap) and you will be left with acetanilide.
2)
formula equation: Pb(NO₃)₂(aq) + 2KI(aq) ----> PbI₂(s) + 2KNO₃(aq)
total ionic equation: Pb⁺² + 2NO₃⁻¹ + 2K⁺¹ + 2I⁻¹----> PbI₂(s) + 2K⁺¹ + 2NO₃⁻¹
net ionic equation: Pb⁺² + 2 I⁻¹----> PbI₂(s)
3)
formula equation: Zn(NO₃)₂(aq) + K₂CO₃(aq) -----> ZnCO₃(s) + 2KNO₃(aq)
total ionic equation: Zn⁺² + 2NO₃⁻¹ + 2K⁺¹ + CO₃⁻² ---> ZnCO₃ (s) + 2K⁺¹ + 2NO₃⁻¹
net ionic equation: Zn⁺² + CO₃⁻² ----> ZnCO₃ (s)
note: if I did not specify the state of the molecule in the reaction, you can assume they are aqueous unless state otherwise.
