Answer:
1) When 6.97 grams of sodium(s) react with excess water(l), 56.0 kJ of energy are evolved.
2) When 10.4 grams of carbon monoxide(g) react with excess water(l), 1.04 kJ of energy are absorbed.
Explanation:
1) The following thermochemical equation is for the reaction of sodium(s) with water(l) to form sodium hydroxide(aq) and hydrogen(g).
2 Na(s) + 2H₂O(l) ⇒ 2NaOH(aq) + H₂(g) ΔH = -369 kJ
The enthalpy of the reaction is negative, which means that 369 kJ of energy are evolved per 2 moles of sodium. The energy evolved for 6.97 g of Na (molar mass 22.98 g/mol) is:
2) The following thermochemical equation is for the reaction of carbon monoxide(g) with water(l) to form carbon dioxide(g) and hydrogen(g).
CO(g) + H₂O(l) ⇒ CO₂(g) + H₂(g) ΔH = 2.80 kJ
The enthalpy of the reaction is positive, which means that 2.80 kJ of energy are absorbed per mole of carbon monoxide. The energy evolved for 10.4 g of CO (molar mass 28.01 g/mol) is:
Enthalpy is the change in energy. A cold pack will react endothermically and enthalpy will be positive and a heat pack will have negative enthalpy. You cannot determine which has more change in enthalpy unless you measure the temperature change. Eg. a heat pack went from 25c to 35c will have greater change in enthalpy then a cold pack going from 25 to 20c because the net temperature difference is greater
To solve this question, we first need to know the mass of one mole of mercury. This can be done by checking the periodic table.
From the periodic table, we can see that:
molar mass of mercury = 200.59 grams/mole.
From the measurements, the chemist found that the participated amount of mercury is 0.02 moles.
We can simply determine the mass of 0.02 moles by doing cross multiplication as follows:
mass of 0.02 moles = (0.02 x 200.59) / 1 = 4.0118 grams
Rounding the answer to 2 significant digits, we get:
mass of 0.02 moles = 4.01 grams
If the water vapor content stays the same and the temperature drops, the relative humidity increases. If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn't require as much moisture to become saturated as warmer air.
Answer: See explanation
Explanation:
Based on the information given in the question, the ranking from the first step to the last step goes as follows:
1. Dissolution of salt into cations and anions
2. Hydration of anions
3. Hydration of cations
4. Dissolved cations and anions begin to deposit as a solid salt.
5. Rate of dissolution is equal to the rate of recrystallization.
