Need to calculate the resistance accross membrane in water

In summary, the speaker is a chemist who has prepared an ionic membrane and placed it in a homemade acrylic cell with 0.1M NaCl. They applied a DC voltage of 9.6V using a 9V battery and measured a voltage of 4.45V and current of 0.93mA using a multimeter. They are unsure if they can calculate the resistance from the voltage drop and are seeking guidance. The conversation also mentions the strange result of the battery being loaded down to 4.45V with less than 1mA of current and raises questions about the experimental method.
  • #1
M. Hammad Khan
1
0
Hello everybody,
I am chemist. and I prepare ionic membrane and placed in a home made acrylic cell containing 0.1M NaCl separated into two portions by ionic membrane. I applied DC voltage of 9.6V (using 9V battery). Using multi-meter the measured DC voltage in water was 4.45V. The distance between the electrodes is 20cm. The measured amperes were 0.93mA. Can I calculate the resistance from voltage drop? and how? Please help or guide if I m doing wrong.
 
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  • #2
It's not clear to me what you are doing, but a diagram might help. My best guess is that the resistance is 4.45V divided by 0.93 mA which is 4785 Ohms. But without an understanding of what you are doing, that caculcation might not be the right one, or the experimental method could be fundamentally flawed.

The thing that seems strange is the battery is loaded down to 4.45 V with less than 1 mA of current. Not sure why this is.
 
  • #3
M. Hammad Khan said:
Using multi-meter the measured DC voltage in water was 4.45V.
Voltage is always between two points.
"voltage in water" is just three words that convey no information.

Where were the two voltmeter leads physically placed ?
 

Related to Need to calculate the resistance accross membrane in water

1. What is the purpose of calculating the resistance across a membrane in water?

The resistance across a membrane in water is an important measure in determining the efficiency of a membrane in separating different substances. It can also help in understanding the transport of ions and molecules across the membrane, which is essential in many biological and industrial processes.

2. How is the resistance across a membrane in water calculated?

The resistance across a membrane in water can be calculated using Ohm's law, which states that resistance is equal to the voltage divided by the current. In this case, the voltage is the potential difference across the membrane and the current is the flow of ions or molecules through the membrane.

3. What factors can affect the resistance across a membrane in water?

The resistance across a membrane in water can be affected by various factors such as the thickness and composition of the membrane, the concentration and size of the molecules or ions, and the temperature and pH of the water. The presence of other substances in the water can also impact the resistance.

4. How does the resistance across a membrane in water relate to membrane permeability?

The resistance across a membrane in water and membrane permeability are inversely related. This means that as resistance increases, permeability decreases and vice versa. This relationship is important in understanding the selectivity of a membrane and its ability to allow certain substances to pass through while blocking others.

5. What are some applications of calculating the resistance across a membrane in water?

The calculation of resistance across a membrane in water has many practical applications. It is used in the design and optimization of water filtration systems, such as reverse osmosis and nanofiltration. It is also important in the study of biological processes such as osmosis and ion transport in cells. Additionally, it is used in the development of new materials for membrane-based technologies.

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