The semi-permeable membrane allows [positively/negatively] charged sodium [ions/atoms] through into the other electrolytic half-cell. The electrode in this half-cell is connected to the negative terminal of the battery. The battery [pulls electrons away from/pushes electrons into] it, charging the electrode [positively/negatively/neutrally]. This causes water molecules to react at this electrode. The water molecules [lose/accept] the electrons. We say the water is [oxidized/reduced]. These electrons cause water to change into gas (H2) and [positively/negatively/neutrally] charged hydroxyl ions (OH-). These hydroxyl ions are dissolved in water, as are the sodium ions which moved through the membrane. Sodium ions and hydroxyl ions are therefore present in the solution. We call this a sodium hydroxide solution. The electrode at which reduction occurs is called the [cathode/anode]. In an electrolytic cell, such as this, the battery charges the cathode [positively/negatively].