What is the difference between r and R ?

Explanation

To understand the difference between small r (r) and capital R (R), we can break it down step by step:

### Step 1: Definition of r and R
- **Small r (r)**: This represents the specific gas constant for a particular gas. It is defined as the universal gas constant (R) divided by the molar mass (M) of the gas. The units for r are typically J/(kg·K).

- **Capital R (R)**: This is the universal gas constant. It is a constant that applies to all ideal gases and is used in the ideal gas law. The value of R is approximately 8.314 J/(mol·K) when using moles as the unit of measurement.

### Step 2: Context of Use
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