pH changes with temperature due to the impact on the dissociation of water and the equilibrium of acid-base reactions.

The Relationship Between pH and Temperature: Explained

pH is a measure of the acidity or alkalinity of a solution, with a range from 0 to 14. A pH of 7 is considered neutral, while values below 7 are acidic and values above 7 are alkaline. The pH of a solution can be influenced by various factors, including temperature. In this article, we will explore the relationship between pH and temperature and why pH changes with temperature.


When it comes to pH, temperature plays a crucial role in determining the acidity or alkalinity of a solution. As temperature increases, the pH of a solution can change due to the effect of temperature on the dissociation of ions in the solution. This phenomenon is known as the temperature dependence of pH.

One reason why pH changes with temperature is the effect of temperature on the dissociation of weak acids and bases. In a solution containing a weak acid, for example, an increase in temperature can lead to an increase in the dissociation of the acid molecules, resulting in a higher concentration of hydrogen ions (H+) and a decrease in pH. Conversely, a decrease in temperature can lead to a decrease in the dissociation of the acid molecules, resulting in a lower concentration of hydrogen ions and an increase in pH.

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Similarly, in a solution containing a weak base, an increase in temperature can lead to an increase in the dissociation of the base molecules, resulting in a higher concentration of hydroxide ions (OH-) and an increase in pH. On the other hand, a decrease in temperature can lead to a decrease in the dissociation of the base molecules, resulting in a lower concentration of hydroxide ions and a decrease in pH.

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Another reason why pH changes with temperature is the effect of temperature on the ionic product of water. The ionic product of water, Kw, is a constant value at a given temperature. However, as temperature changes, the value of Kw also changes, leading to a change in the concentration of hydrogen ions and hydroxide ions in the solution, and consequently, a change in pH.

Furthermore, the effect of temperature on the solubility of gases in water can also influence the pH of a solution. As temperature increases, the solubility of gases in water decreases, leading to a decrease in the concentration of dissolved gases such as carbon dioxide. This can result in a decrease in the formation of carbonic acid, which is responsible for lowering the pH of the solution.

Instrument model FET-8920
Measurement range Instantaneous flow (0~2000)m3/h
Accumulative flow (0~99999999)m3
Flow rate (0.5~5)m/s
Resolution 0.001m3/h
Accuracy level Less than 2.5% RS or 0.025m/s.whichever is the largest
Conductivity >20μS/cm
(4~20)mA output Number of channels Single channel
Technical features Isolated,reversible,adjustable, meter/transmission dual mode
Loop resistance 400Ω(Max), DC 24V
Transmission accuracy ±0.1mA
Control output Number of channels Single channel
Electrical contact Semiconductor photoelectric relay
Load capacity 50mA(Max), DC 30V
Control mode Instantaneous amount upper/lower limit alarm
Digital output RS485(MODBUS protocol ),Impulse output1KHz
Working power Power supply DC 9~28V
source Power Consumption ≤3.0W
  Diameter DN40~DN300(can be customized)
Working environment Temperature:(0~50) ℃; Relative humidity: ≤85%RH(none condensation)
Storage environment Temperature:(-20~60) ℃; Relative humidity: ≤85%RH(none condensation)
Protection grade IP65
Installation method Insertion pipeline installation

In conclusion, the relationship between pH and temperature is a complex one, influenced by various factors such as the dissociation of weak acids and bases, the ionic product of water, and the solubility of gases in water. Understanding how pH changes with temperature is important in various fields, including chemistry, biology, and environmental science. By considering the effects of temperature on pH, scientists can better interpret experimental results and make more accurate predictions about the behavior of solutions at different temperatures.

ROC-2315 ro controller instruction (220V)
Model ROC-2315
Single detection Dry Contact input Raw water no water protection
(six channels) Low-pressure protection
  High-pressure protection
  Pure water tank high level
  External control mode signal
  Running reset
Control port Dry Contact output Raw water pump SPST-NO low capacity : AC220V/3A Max ;AC110V/5A Max
(five channels) Inlet valve  
  High pressure pump  
  Flush valve  
  Conductivity over-limit drainge valve  
Measurement detection point Product water conductivity and with Automatic Temperature compensation (0~50)℃
Measurement range Conductivity : 0.1~200μS/cm/1~2000μS/cm/10~999μS/cm (with different conductivity sensor )
Product water temp. : 0~50℃
Accuracy 1.5 level
Power supply AC220V (±10%) , 50/60Hz
Working environment Temperature:(0~50)℃ ;
Relative Humidity :≤85%RH (no condensation )
Dimension 96×96×130mm( height ×width×depth)
Hole size 91×91mm(height ×width)
Installation Panel mounted ,fast installtion
Certification CE

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