# Reading Chemistry Data Tables and Graphs
The ACT Science section tests your ability to read and interpret scientific data — you don't need to memorise chemistry facts. This guide teaches you how to efficiently extract information from chemistry-related data tables, graphs, and figures.
1. Types of Data Representations
Tables
- Rows represent individual experiments or conditions
- Columns represent variables (independent, dependent, controlled)
- Read headers carefully — they tell you what each column measures
- Note units in headers or footnotes
Graphs
- X-axis: independent variable (what was changed)
- Y-axis: dependent variable (what was measured)
- Title/caption: explains what's being shown
- Legend: identifies different data series
Diagrams
- Apparatus setups, molecular structures, phase diagrams
- Arrows indicate direction of flow or change
2. Key Skills
Reading Values
- Find the correct row/column intersection in tables
- Use gridlines on graphs to read precise values
- Interpolate between data points if needed
Identifying Trends
- As X increases, does Y increase, decrease, or stay the same?
- Is the relationship linear, exponential, or inverse?
- Look for patterns across multiple experiments
Comparing Data Series
- When two lines are on the same graph, compare their values at specific points
- Note which is higher/lower and when they cross
3. Common Chemistry Data Types
| Data Type | What It Shows |
|---|---|
| Temperature vs Time | Heating/cooling curves, reaction rates |
| Concentration vs Time | Reaction progress, rate studies |
| pH vs Volume added | Titration curves |
| Volume of gas vs Time | Rate of gas-producing reactions |
| Absorbance vs Wavelength | Spectroscopy data |
| Solubility vs Temperature | Solubility curves |
4. Worked Example
A table shows:
| Trial | Temperature (°C) | Time to React (s) | Volume of Gas (mL) |
|---|---|---|---|
| 1 | 20 | 120 | 50 |
| 2 | 30 | 65 | 50 |
| 3 | 40 | 30 | 50 |
| 4 | 50 | 15 | 50 |
Q: How does temperature affect reaction time? A: As temperature increases, reaction time decreases (reaction is faster).
Q: What volume of gas would you expect at 35°C? A: 50 mL — the volume is constant regardless of temperature.
5. Practice Questions
- From a graph of solubility vs temperature, at what temperature does KNO₃ have a solubility of 100 g/100 mL?
- A table shows pH values for different solutions. Which solution is most acidic?
- Two experiments produce different amounts of gas. Identify which variable was changed.
- From a heating curve, identify the melting and boiling points.
- A graph shows absorbance vs concentration. Estimate the concentration when absorbance = 0.35.
Want to check your answers and get step-by-step solutions?
6. ACT Tips
- Read the passage QUICKLY — focus on understanding the experimental setup
- Go to the questions first; refer back to the data as needed
- Don't overthink — the answer is usually directly in the data
- If asked to predict beyond the data range, extend the trend
- Pay attention to units and axis labels