Mathematical Relationships · Chemistry Reference Tables (2025 Edition)
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The Mathematical Relationships table from the Reference Tables for Physical Science: Chemistry (2025 Edition) gives three relationships and a note defining STP. The temperature and pressure rows support HS-PS1-9 (gas law calculations need kelvin, and STP is defined here); the mole row supports HS-PS1-7 and the concentration calculations in HS-PS1-10.
| Temperature | K = °C + 273.15 |
|---|---|
| Pressure | 1 atm = 101.3 kPa |
| 1 mole | = molar mass (g) |
| = 6.02 × 1023 particles | |
| = 22.4 L (ideal gas at STP) |
Note: Standard Temperature and Pressure (STP) conditions are 273.15 K and 1 atm.
What the relationships table shows
Temperature. K = °C + 273.15 converts Celsius temperatures to kelvin, which is what the combined gas law needs. The 2011 edition rounded the conversion to 273; the 2025 edition uses 273.15, and the answer keys of the released questions do too (298.15 K for 25 °C).
Pressure. 1 atm = 101.3 kPa converts between the two pressure units on the exam. The 2025 tables give pressures in kilopascals and atmospheres only; there is no mm Hg or torr.
1 mole. One mole of a substance has a mass equal to its molar mass in grams (the sum of the average atomic masses from the Periodic Table of the Elements), contains 6.02 × 1023 particles (atoms, molecules, formula units or ions), and, for an ideal gas at STP, occupies 22.4 L. The first relationship is the one every mass–mole stoichiometry calculation uses; the third turns up when a gas volume is asked for (August 2026 Q3).
STP. Standard temperature and pressure is 273.15 K and 1 atm (101.3 kPa). HS-PS1-9's clarification statement allows real gases at conditions near STP.
Regents Exam Questions
Released Regents questions that cannot be answered without this table, listed by exam. Each link opens the question with its answer key; the standard is the one the question assesses.
| Exam | Cluster | Question | Standard | Row |
|---|---|---|---|---|
| August 2026 Chemistry Regents | Electricity Generation in New York State | Question 3 | HS-PS1-7 | Mole relationships |
| Catalytic Converter in Cars | Question 31 | HS-PS1-7 | Mole relationships | |
| Parade of Balloons | Question 42 | HS-PS1-9 | K = °C + 273.15 | |
| June 2026 Chemistry Regents | Chemistry of Beverages | Question 6 | HS-PS1-7 | Mole relationships |
| Balloon Arches | Question 24 | HS-PS1-7 | Mole relationships | |
| Balloon Arches | Question 26 | HS-PS1-9 | K = °C + 273.15 | |
| Clock Reaction | Question 32 | HS-PS1-10 | Mole relationships | |
| Chemistry sample clusters (spring 2025) | Smartphone Chemistry | Question 3 | HS-PS1-7 | Mole relationships |
| A Profitable Blueberry Field | Question 4 | HS-PS1-7 | Mole relationships |