Start with this short video, then scroll down for the full guide.
Why This Matters for Nursing: Understanding reactions and pH is essential for interpreting blood gases, understanding medication interactions, and recognizing acid-base imbalances that can be life-threatening.
A chemical reaction occurs when substances interact to form new substances with different properties.
General form: Reactants → Products
pH Scale: "pH = Power of Hydrogen" - Low pH = ACIDIC (more H⁺) - High pH = BASIC (less H⁺) - pH 7 = NEUTRAL
Blood pH: 7.35-7.45 (slightly basic) "Basic blood keeps you alive"
| Type | Description | Example |
|---|---|---|
| Synthesis | A + B → AB | 2H₂ + O₂ → 2H₂O |
| Decomposition | AB → A + B | 2H₂O → 2H₂ + O₂ |
| Single replacement | A + BC → AC + B | Zn + 2HCl → ZnCl₂ + H₂ |
| Double replacement | AB + CD → AD + CB | NaCl + AgNO₃ → AgCl + NaNO₃ |
| Combustion | Fuel + O₂ → CO₂ + H₂O | CH₄ + 2O₂ → CO₂ + 2H₂O |
Enzymes are biological catalysts that: - Speed up reactions without being consumed - Lower activation energy needed - Are specific to certain reactions - Are proteins
| Factor | Effect |
|---|---|
| Temperature | Too high → denatures enzyme |
| pH | Each enzyme has optimal pH |
| Substrate concentration | More substrate → faster (until saturated) |
| Property | Acids | Bases |
|---|---|---|
| pH | Below 7 | Above 7 |
| H⁺ concentration | High | Low |
| OH⁻ concentration | Low | High |
| Taste | Sour | Bitter |
| Examples | HCl, vinegar, lemon | NaOH, bleach, soap |
| Substance | Type | Location/Function |
|---|---|---|
| Hydrochloric acid (HCl) | Acid | Stomach acid |
| Bicarbonate (HCO₃⁻) | Base | Blood buffer |
| Carbonic acid (H₂CO₃) | Acid | Blood buffer |
| pH | Examples |
|---|---|
| 0-2 | Battery acid, stomach acid |
| 3-4 | Vinegar, soda |
| 5-6 | Coffee, urine |
| 7 | Pure water (neutral) |
| 7.35-7.45 | Blood (normal) |
| 8-9 | Baking soda, seawater |
| 10-12 | Ammonia, bleach |
| 13-14 | Lye, drain cleaner |
Buffers resist changes in pH by absorbing or releasing H⁺.
Blood buffer system: - Carbonic acid (H₂CO₃) ↔ Bicarbonate (HCO₃⁻) + H⁺ - If blood too acidic: Bicarbonate absorbs H⁺ - If blood too basic: Carbonic acid releases H⁺
| Condition | Blood pH | Common Causes |
|---|---|---|
| Acidosis | < 7.35 | Diabetic ketoacidosis, respiratory failure |
| Alkalosis | > 7.45 | Hyperventilation, vomiting |
Normal blood pH: 7.35 - 7.45
Reaction: 2Na + Cl₂ → 2NaCl
Step 1 — Count the reactants and products. On the LEFT side of the arrow (reactants): 2 things — sodium (Na) and chlorine gas (Cl₂). On the RIGHT side (products): 1 thing — sodium chloride (NaCl, table salt).
Step 2 — Apply the pattern matching. Ask: are things coming together or breaking apart? - Two separate things (Na and Cl₂) are combining → forming one new product (NaCl) - Pattern: A + B → AB - This is synthesis (also called a combination reaction). Like building a car — you take parts and put them together.
Step 3 — Confirm by eliminating other types. - Decomposition would be AB → A + B (breaking apart). Here things are coming together, not apart. ✗ - Single replacement would be A + BC → AC + B (one element kicks out another). Not the case here. ✗
Answer: Synthesis — Two reactants (Na and Cl₂) combine into one product (NaCl).
The worked examples and practice problems are the part that actually prepares you for the TEAS.
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