Chapter 8 Flashcards
(25 cards)
What is global warming?
The recent and ongoing rise in global average temperature near Earth’s surface.
What is a major greenhouse gas responsible for global warming?
Carbon dioxide (CO2).
How much has atmospheric CO2 increased since 1880?
By 38%.
How much has Earth’s average temperature increased since 1880?
About 1.0°C (1.9°F).
What is the Paris Agreement?
A 2015 treaty signed by 196 countries to limit global warming to 1.5°C above pre-industrial levels.
What are examples of greenhouse gases?
CO2, CH4, N2O, CFCs, HFCs, PFCs, SF6, NF3.
How do livestock contribute to global warming?
Cows, sheep, and goats produce methane during digestion and release it through belching.
Which greenhouse gas is more potent: methane or CO2?
Methane is more potent than CO2.
Which greenhouse gas has a longer lifetime: methane or CO2?
CO2 has a longer lifetime than methane in the atmosphere.
What is the most abundant greenhouse gas?
Water vapor (H2O).
What is the role of stratospheric ozone (O3)?
It protects life from harmful UV radiation.
Is the greenhouse effect necessary for life?
Yes, it helps maintain Earth’s temperature.
What is stoichiometry?
The quantitative relationship between reactants and products in a chemical reaction.
How many moles of N2 are required to react with 6 moles of H2?
2 moles of N2 (3H2 : 1N2 ratio).
How many moles of H2 are needed to form 10 moles of NH3?
15 moles of H2 (2NH3 : 3H2 ratio).
What is the limiting reactant?
The reactant that is completely consumed in a reaction, limiting the amount of product.
What is theoretical yield?
The maximum amount of product that can be made based on the limiting reactant.
What is actual yield?
The amount of product actually produced in a reaction, determined experimentally.
Why is actual yield usually less than 100%?
Some product is lost or does not form during the reaction.
How do you calculate percent yield?
(Actual yield / Theoretical yield) × 100.
What is enthalpy (ΔHrxn)?
The thermal energy emitted or absorbed by a reaction at constant pressure.
What is the sign of ΔHrxn for an exothermic reaction?
Negative (-), because heat is emitted.
What is the sign of ΔHrxn for an endothermic reaction?
Positive (+), because heat is absorbed.
How much heat is emitted when 4 moles of CaO react in CaO + H2O → Ca(OH)2 (ΔHrxn = -63.7 kJ)?
-254.8 kJ (4 × -63.7 kJ).
