Is there a relationship between the pH and the conductivity of a sample?
样品的pH与电导率之间是否存在着一定关系？
Yes, pH and conductivity are related, but not linearly or in an absolute manner. A
pH sensor responds solely to H+ in a solution, whereas in conductivity the
sensors measure the activity of all charged ions (anions and cations) present in a solution. The higher the concentration of ions, the higher the conductivity. Furthermore, the mobility of an ion has an enhancing impact on conductivity. Among the common ions in a solution, the most mobile cation is the Hydrogen ion [H+] with a value of 350 units, and the most mobile anion is the Hydroxyl ion [OH-], 199 units. Other common ions have values ranging between 40 and 80 units. This means strongly acidic (or strongly basic) solutions will have high conductivities. Since pH is a measure of the concentration of Hydrogen ions, the following rules apply: In acidic solutions (< pH 7): the lower the pH (i.e. the higher the H+ concentration) the higher the conductivity. In alkaline solutions (> pH 7): the conductivity increases with increase of the pH (increase of OH- ion). Neutral pH (pH 7) is due to equal concentration of H+ and OH- ions. But it does not mean the solution does not contain any other ions that would contribute to the conductivity of the solution. Let's consider an example: pH of deionized water is theoretically 7.0 and conductivity is 0.055 µS/cm. If you add NaCl salt to it, the resulting NaCl solution will still be of neutral pH, but the conductivity of the solution could greatly increase depending on the amount of NaCl added. In summary: pH and conductivity of a sample must be determined separately for each of the samples and cannot be theoretically correlated.
是的，pH与电导率相关，但是非线性或绝对相关。
pH计仅对溶液内的H+响应，而对于电导率而言，
电极测量溶液内所有带电离子（阴离子和阳离子）的活性。离子浓度越高，则电导率越高。 另外，离子的流动性会对电导率产生更大影响。在溶液中常见的离子中，流动性最强的阳离子为氢离子[H+]，其值为350个单位，流动性最强的阴离子为羟基离子[OH-]，其值为199个单位。其他常见离子的值在40至80个单位之间。这意味着强酸性（或强碱性）溶液将具有高电导率。由于pH是氢离子浓度的量度，因此采用以下规则： 在酸性溶液中（pH 7以下）：pH值越低（即：H+浓度越高），则电导率越高。 在碱性溶液中（pH 7以上）：pH值越高（OH-离子增多），则电导率越高。 中性pH（pH 7）是因为H+与OH-离子浓度相等。但是，这并不意味着溶液内不含有将会对溶液的电导率产生作用的其他任何离子。 现在举一个例子：去离子水的pH值理论上为7.0，电导率为0.055 µS/cm。如果向其中添加NaCl盐，则产生的NaCl溶液的pH值将仍为中性，但溶液的电导率可能会随着NaCl量的增加而明显提高。 总而言之：必须为不同样品单独测定pH值和电导率，并且不能在理论上相关联。