ACIDS & BASES BASICS
Q: This is the pH value that is considered neutral on the pH scale.
7
In a chemical equation, reactants appear on this side of the arrow.
Left
This percentage represents the nitrogen content in urea fertilizer.
46%
Farmers use this soil amendment, typically calcium carbonate, to raise soil pH.
agricultural lime (or lime)
In this reaction type, a fuel burns rapidly with oxygen, releasing energy, CO₂, and H₂O.
combustion
This sign of a chemical reaction occurs when you see bubbles or fizzing, such as when lime is added to acidic soil.
gas production
Q: Acids release these ions when dissolved in water.
H+ ions (hydrogen ions)
This law states that the total mass of reactants equals the total mass of products.
Law of Conservation of Mass
This soil enzyme, produced by bacteria, catalyzes the breakdown of urea.
urease
When soil pH is too high (above 7.5), this essential nutrient reacts with calcium to form insoluble compounds.
phosphorus
This reaction type follows the pattern A + B → AB, where substances combine to form a single product.
synthesis (or combination)
Farmers ferment corn or grass in airtight conditions to create this preserved, high-energy livestock feed.
silage
Q: This pH range is ideal for most crop growth.
6-7
In the equation CO(NH₂)₂ + H₂O → CO₂ + 2NH₃, these are the two reactants.
urea and water
This two-step process converts ammonium (NH₄⁺) into nitrate (NO₃⁻) using soil bacteria.
nitrification
This type of reaction occurs when lime neutralizes acidic soil.
neutralization reaction (or double replacement)
Urea breaking down in soil is an example of this reaction type, which follows the pattern AB → A + B.
decomposition
This process uses yeast to break down glucose from corn into ethanol and carbon dioxide for biofuel production.
fermentation
This agricultural material has a pH above 7 and is used to raise soil pH: agricultural lime, wood ash, or ammonia.
bases (or any of the three examples)
When urea breaks down in soil, these two products are formed.
ammonia (NH₃) and carbon dioxide (CO₂)
These two types of bacteria carry out nitrification: one converts ammonium to nitrite, the other converts nitrite to nitrate.
Nitrosomonas and Nitrobacter
Nitrification releases these ions, which over time can lower soil pH when ammonia-based fertilizers are repeatedly used.
H+ ions (hydrogen ions)
The Haber-Bosch process that combines N₂ and H₂ to make ammonia fertilizer is this type of reaction.
synthesis
A compost pile feels warm because decomposition reactions are this type, meaning they release heat energy.
exothermic
When soil pH is too low, this toxic element dissolves and damages plant roots.
aluminum
In a chemical reaction, atoms are not created or destroyed; instead this happens to them.
rearranged (or recombined into new combinations)
This is the loss of ammonia gas from soil into the atmosphere when surface-applied urea reacts under warm, dry conditions.
volatilization
When lime (CaCO₃) reacts with acidic soil, these three products are formed: calcium ions, water, and this gas.
carbon dioxide (CO₂)
In this reaction type, ions from two compounds switch partners, following the pattern AB + CD → AD + CB.
double replacement (or double displacement)
When phosphate fertilizers react with calcium in high-pH soils, this forms—a solid that makes phosphorus unavailable to plants.
precipitate (or calcium phosphate)