Key Takeaways
- Chemical reactions involve the breaking and forming of chemical bonds, producing new substances with different properties
- The law of conservation of mass states that matter cannot be created or destroyed — equations must be balanced
- Types of reactions: synthesis (A+B→AB), decomposition (AB→A+B), single replacement, double replacement, combustion
- Reaction rate is affected by temperature, concentration, surface area, and catalysts
- Acids donate H+ ions (pH < 7), bases accept H+ ions or donate OH- (pH > 7), and buffers resist pH changes
- A solution consists of a solute (dissolved substance) and a solvent (dissolving substance, usually water)
- Concentration can be expressed as molarity (mol/L), percent composition, or parts per million
- Oxidation is the loss of electrons; reduction is the gain of electrons (OIL RIG: Oxidation Is Loss, Reduction Is Gain)
Chemical Reactions & Solutions
Chemical reactions and solution chemistry are directly relevant to nursing. From understanding how medications interact in the body to interpreting lab values and managing IV fluids, these concepts have daily clinical applications.
Types of Chemical Reactions
| Type | General Form | Example |
|---|---|---|
| Synthesis | A + B → AB | 2H2 + O2 → 2H2O |
| Decomposition | AB → A + B | 2H2O → 2H2 + O2 |
| Single replacement | A + BC → AC + B | Zn + CuSO4 → ZnSO4 + Cu |
| Double replacement | AB + CD → AD + CB | NaCl + AgNO3 → NaNO3 + AgCl |
| Combustion | Fuel + O2 → CO2 + H2O | CH4 + 2O2 → CO2 + 2H2O |
Balancing Chemical Equations
The law of conservation of mass states that matter cannot be created or destroyed. In a balanced equation, the number of atoms of each element must be equal on both sides.
Steps to balance an equation:
- Write the unbalanced equation
- Count atoms of each element on both sides
- Add coefficients (numbers in front of formulas) to equalize
- Check that all elements are balanced
- Ensure coefficients are in the lowest whole-number ratio
Example: Balance: H2 + O2 → H2O
- Unbalanced: H=2, O=2 on left; H=2, O=1 on right
- Add coefficient: 2H2 + O2 → 2H2O
- Check: H=4, O=2 on both sides ✓
Factors Affecting Reaction Rate
| Factor | Effect |
|---|---|
| Temperature | Higher temperature → faster reaction (more kinetic energy) |
| Concentration | Higher concentration → faster reaction (more collisions) |
| Surface area | Greater surface area → faster reaction (more exposure) |
| Catalyst | Lowers activation energy → faster reaction (not consumed) |
| Pressure | Higher pressure → faster reaction (gases only) |
Acids, Bases & pH
| Property | Acid | Base |
|---|---|---|
| pH | Less than 7 | Greater than 7 |
| H+ ions | Donates H+ | Accepts H+ |
| OH- ions | Low concentration | High concentration (donates OH-) |
| Taste | Sour | Bitter |
| Feel | — | Slippery |
| Litmus | Turns blue litmus red | Turns red litmus blue |
| Examples | HCl, H2SO4, vinegar | NaOH, KOH, ammonia |
Neutralization reaction: Acid + Base → Salt + Water
- HCl + NaOH → NaCl + H2O
Buffers are substances that resist changes in pH. In the body, the bicarbonate buffer system (H2CO3/HCO3-) is the primary buffer that maintains blood pH between 7.35 and 7.45.
Solutions
A solution is a homogeneous mixture of a solute (substance being dissolved) and a solvent (substance doing the dissolving):
| Term | Definition | Example |
|---|---|---|
| Solute | Substance dissolved | Sugar, salt, medication |
| Solvent | Substance doing the dissolving | Water (universal solvent) |
| Concentration | Amount of solute per amount of solution | 0.9% NaCl (normal saline) |
| Dilute | Low ratio of solute to solvent | |
| Concentrated | High ratio of solute to solvent | |
| Saturated | Maximum solute dissolved at a given temperature |
Concentration Units
| Unit | Formula | Example |
|---|---|---|
| Percent (w/v) | (mass of solute / volume of solution) x 100 | 5% dextrose = 5 g per 100 mL |
| Molarity (M) | moles of solute / liters of solution | 1 M NaCl = 1 mol NaCl per liter |
| Parts per million (ppm) | mg/L or mg/kg | Fluoride in water: ~1 ppm |
Clinically Important Solutions
| Solution | Composition | Use |
|---|---|---|
| Normal saline (NS) | 0.9% NaCl | Isotonic IV fluid |
| D5W | 5% dextrose in water | Provides calories and free water |
| Lactated Ringer's (LR) | NaCl, KCl, CaCl2, lactate | Isotonic IV fluid for resuscitation |
| Half-normal saline | 0.45% NaCl | Hypotonic IV fluid |
Oxidation-Reduction (Redox) Reactions
- Oxidation: Loss of electrons (OIL: Oxidation Is Loss)
- Reduction: Gain of electrons (RIG: Reduction Is Gain)
- OIL RIG is the mnemonic for remembering this concept
- In every redox reaction, one substance is oxidized and another is reduced
- Example: Cellular respiration is a redox reaction — glucose is oxidized, oxygen is reduced
The reaction 2H2 + O2 → 2H2O is an example of:
A solution with a pH of 3 is:
In a solution, the substance being dissolved is called the:
The law of conservation of _____ states that matter cannot be created or destroyed in a chemical reaction.
Type your answer below
What is the product of a neutralization reaction between an acid and a base?
Match each type of chemical reaction to its general form.
Match each item on the left with the correct item on the right
Which factor does NOT increase the rate of a chemical reaction?