Payment & Shipping Terms:
|Item:||Aquarium Ph Meter||Size:||15.5x2.3x3.1cm|
|Power:||3*1.5V(AG-13) Button Cell Battery||Warranty:||1 Years|
What does pH actually mean?
The pH (always written little p, big H) of a substance is an indication of how many hydrogen ions it forms in a certain volume of water. There's no absolute agreement on what "pH" actually stands for, but most people define it as something like "power of hydrogen" or "potential of hydrogen." Now this is where it gets confusing for those of you who don't like math. The proper definition of pH is that it's minus the logarithm of the hydrogen ion activity in a solution (or, if you prefer, the logarithm of the reciprocal of the hydrogen ion activity in a solution). Gulp. What does that mean?
It's simpler than it sounds. Let's unpick it a bit at a time. Suppose you have some liquid sloshing about in your aquarium and you want to know if it's safe for those angelfish you want to keep. You get your pH meter and stick it into the "water" (which in reality is a mixture of water with other things dissolved in it). If the water is very acidic, there will be lots of active hydrogen ions and hardly any hydroxide ions. If the water is very alkaline, the opposite will be true. Now if you have a thimble-full of the water and it has a pH of 1 (it's unbelievably, instantly, fish-killingly acidic), there will be one million times (10 to the power of 6, written 106) more hydrogen ions than there would be if the water were neutral (neither acidic nor alkaline), with a pH of 7. That's because a pH of 1 means 101 (which is just 10), and a pH of 7 means 107 (10 million), so dividing the two gives us 106 (one million). There will be 10 million million (1013) more hydrogen ions than if the water were extremely alkaline, with a pH of 14. Maybe you can start to see now where those mysterious pH numbers come from?
Suppose we decide to invent a scale of acidity and start it off at very acidic and call that 1. Then something neutral will have far fewer (one millionth or 10−6 times as many hydrogen ions) and something alkaline will have fewer still (that's one 10 trillionth, or one 10 million millionth, or 10−13 times as many). Dealing with all these millions and billions and trillions is confusing and daft so we just take a logarithm of the number of hydrogen ions and refer to the power of ten we get in each case. In other words, the pH means simply looking at the (probably gigantic) number of hydrogen ions, taking the power of 10, and removing the minus sign. That gives us a pH of 1 for extremely acidic, pH 7 for neutral, and pH 14 for extremely alkaline. "Extremely alkaline" is another way of saying incredibly weakly acidic.
How does a pH meter work?
If you're using litmus paper, none of this matters. The basic idea is that the paper turns a slightly different color in solutions between pH 1 and 14 and, by comparing your paper to a color chart, you can simply read off the acidity or alkalinity without worrying how many hydrogen ions there are. But a pH meter somehow has to measure the concentration of hydrogen ions. How does it do it?
An acidic solution has far more positively charged hydrogen ions in it than an alkaline one, so it has greater potential to produce an electric current in a certain situation—in other words, it's a bit like a battery that can produce a greater voltage. A pH meter takes advantage of this and works like a voltmeter: it measures the voltage (electrical potential) produced by the solution whose acidity we're interested in, compares it with the voltage of a known solution, and uses the difference in voltage (the "potential difference") between them to deduce the difference in pH.
A typical pH meter has two basic components: the meter itself, which can be a moving-coil meter (one with a pointer that moves against a scale) or a digital meter (one with a numeric display), and either one or two probes that you insert into the solution you're testing. To make electricity flow through something, you have to create a complete electrical circuit; so, to make electricity flow through the test solution, you have to put two electrodes (electrical terminals) into it. If your pH meter has two probes (like the one in the photo at the top of this article), each one is a separate electrode; if you have only one probe, both of the two electrodes are built inside it for simplicity and convenience.
The electrodes aren't like normal electrodes (simple pieces of metal wire); each one is a mini chemical set in its own right. The electrode that does the most important job, which is called the glass electrode, has a silver-based electrical wire suspended in a solution of potassium chloride, contained inside a thin bulb (or membrane) made from a special glass containing metal salts (typically compounds of sodium and calcium). The other electrode is called the reference electrode and has a potassium chloride wire suspended in a solution of potassium chloride.
|Accuracy||±0.1 PH(at 20°C/ 68°F)|
|Batteries||3*1.5V ( AG-13 Button Battery)|
|Life||approx 700 hours of use|
|Relative Humidity||less than 95%|
Q1. What is your terms of packing?
A: Generally, we pack our goods in neutral PP boxes and brown cartons. If you have legally registered patent, we can pack the goods in your branded boxes after getting your authorization letters.
Q2. What is your terms of payment?
A: T/T 30% as deposit, and 70% before delivery. We'll show you the photos of the products and packages before you pay the balance.
Q3. What is your terms of delivery?
A: EXW, FOB, CFR, CIF.
Q4. How about your delivery time?
A: Generally, it will take 3 to 30 days after receiving your advance payment. The specific delivery time depends on the items and the quantity of your order.
Q5. Can you produce according to the samples?
A: Yes, we can produce by your samples or technical drawings. We can build the molds and fixtures.
Q6. What is your sample policy?
A: We can supply the sample if we have ready parts in stock, and requirethat you my friends, pay the sample cost and the courier cost.
Contact Person: Carey Gao