1. Move the decimal point to the right until you have a number between 1 and 10. In this case, we move the decimal point four places to the right: 3.45

2. Count the number of places you moved the decimal point. We moved it four places.

3. If you moved the decimal point to the right, the exponent of 10 will be negative. Since we moved it to the right, the exponent is -4.

4. Combine the number and the power of ten. This gives us 3.45 x 10⁻⁴.

Therefore, 0.000345 liter in scientific notation is 3.45 x 10⁻⁴ liters.