Chemistry Key Questions
1.
Element
Standard Notation
# Of Electrons
# Of Protons
# Of Neutrons
Sodium
23 11 Na
11
11
12
Chromium
24 Ca
26
26
27 ?
Phosphorus
32 P
15
15
16
2. Fireworks; Which metals burn to produce these colours?
Red – Lithium (Sr)
Blue – Cesium (Cs)
Pink – Potassium (K)
Yellow/Green – Copper (Cu)
Orange – Carbon (Ca)
3. Let’s say that the three bottles contain Fe(NO3)3, BaCl, and AgNO3. These are Iron (III) Nitrate, Barium Chloride, and Silver Nitrate. All of these are white solids that dissolve in water.
We know that silver chloride is highly insoluble in water. So if we reacted an aqueous solution of each of the chemicals with a dilute solution of hydrochloric acid (HCI), the one with Ag+ in it will form AgCl and precipitate as a solid. The other two samples will give no chemical reaction. We have now identified BaCl.
We know that Barium Sulfate is highly insoluble in water. So if we reacted an aqueous solution of each of the chemicals with a dilute solution of sulfuric acid (HS204), the one with the Ba2+ in it will for BaS04 and precipitate as a solid. The other two samples will give no chemical reaction. We have now identified which powder is BaCl.
We know that Iron (III) hydroxide is insoluble in water. So if we reacted an aqueous solution of each of the samples with a dilute solution of sodium hydroxide (NaOH), the one with the Fe3+ in it will form Fe(OH)3 and precipitate as a solid. The other two samples will give no chemical reaction. So we have now identified which powder is Fe(NO3)3.
We have now designed a qualitative analysis experiment in which we have matched up the identities of the three starting solids.
Unit 1- Lesson 2
Chemistry Key Questions
4.
Name
Formula
Cobalt (II) Nitrate
Co(NO3)2
Calcium Phosphate
Ca 3 (PO 4) 2
Disphosphorus trioxide
P203
Ammonium Sulfate
(NH 4) 2 (SO 4)
Gold (III) hydroxide
AuH3O3
Platinum (II) Oxide
PtO
Gallium carbonate