The molecular mass of sodium = 23g
One mole of sodium consists of 23 g of sodium
One mole consists of 1 Avagadro(6.022 x 10^23 molecules) number of molecules
Therefore 23 g consists of 6.022 x 10^23 molecules of Sodium.
Hence 7.45 x 10^3 g of Sodium will consist of x no of molecules of sodium.
x no of molecules =
(7.45 x 10^3 g/23 g) x (6.022 x 10^23)
=1950.6 x 10^ 23 molecules (atoms).
The minerals that one might be examining if you place some hydrochloric acid on a sample and it fizzes are Calcite and Dolomite.
Calcite and dolomite are very similar minerals. Both have the same hardness, the same rhombohedral cleavage, and are found in identical geologic settings. The best way to tell one from the other is the acid test; A drop of 1 M HCl on calcite produces an instant , obvious Fizz; a drop on dolomite produces slow or no obvious bubbling.
Pb(NO3)2 (aq) + 2 NaI (aq) --> PbI2 (s) + 2 NaNO3 (aq)
Starting with with 200.0 grams of Pb(NO3)2 and 120.0 grams of NaI:
A. What is the limiting reagent?
B. How many grams of PbI2 is theoretically formed?
C. How many grams of the excess reactant remains?
D. If 48 grams of NaNO3 actually formed in the reaction, what is the percent yield of this reaction?
Answer:
A. unexpected change in odor
Explanation: Common physical changes include melting, change of size, volume, color, density, and crystal form. Example the classic baking soda and vinegar reaction provides evidence of a chemical change due to the formation of a gas and a temperature change.
