A sample of H2 gas is collected over water by reacting zinc metal with a solution of hydrochloric acid (HCl). In addition to the hydrogen gas, a solution of zinc chloride is also formed. 1. Write the balanced chemical equation for the reaction. Include all states of matter.

2. Write the net ionic equation for this reaction. Include all states of matter.

3. Based on intermolecular forces, why is the H2 gas able to be collected over water rather than being dissolved in the water?

4. If a 0.25 g sample of Zn reacts with excess HCl…
How many moles of HCl will react?

5. How many moles of H2(g) should be produced?

6. The experiment takes place under the following conditions: 300 K, Patm = 777 mmHg, PH2O at 300 K = 26.7 mmHg. How many liters of H2 would be generated under these conditions from the reaction of 0.25 g Zn with excess HCl?

7. How would the amount of H2 collected change if the piece of zinc that reacted had a mass of 0.35 g? Explain.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.