This largely depends on the distance. On a 500m workout, 02:00/500m is good to aim for. For longer distances (1k, 2k, or 5k meters), you might be a bit slower and for shorter ones (50, 100, or 200 meters) a bit faster.
With an increasing distance, your 500m-split will likely decrease. You can check out Paul's law to get an idea of how your pace could behave over time.
To calculate the split, use the following formula:
Split = 500 * (Time in Seconds / Distance in Meters)
To calculate the time, use the following formula:
Time = Split in Seconds * (Distance in Meters / 500)
To calculate the distance, use the following formula:
Time = (Time in Seconds / Split in Seconds) * 500