1, first determine the concentration (0. 1000 ml/L) and volume (1000 ml) of hydrochloric acid standard solution;

2. Calculate the volume V of concentrated hydrochloric acid, where V = 0.1x1000/12 = 8.33 ml;

3. Constant volume: take 8.33 ml concentrated hydrochloric acid, add it into a 1000 ml volumetric flask, and add distilled water to constant volume;

4. Calibration: Calibrate its accurate concentration with standard substance sodium carbonate.