pH is a number that tells you how acid or alkaline a substance is, usually a liquid. Learner books give the scale as 0 to 14. 7 is the middle — like pure water — neither acid nor alkaline.

pH is a number pH是一個數字 that tells you how acid or alkaline a substance is 告訴你一個物質有多酸或多鹼，usually a liquid 通常是液體。Learner books give the scale as 0 to 14 學習用的書把這個量表定為0到14。7 is the middle 7是中間——like pure water 就像純水一樣——neither acid nor alkaline 不酸也不鹼。

Below 7 is acid (lemon juice, vinegar, the acid in your stomach). Above 7 is alkaline (soap, baking soda in water, bleach). Each whole step is a big jump: pH 3 is much more acid than pH 4.

Below 7 is acid 7以下是酸性 (lemon juice, vinegar, the acid in your stomach) （像檸檬汁、醋、你胃裡的酸）。Above 7 is alkaline 7以上是鹼性 (soap, baking soda in water, bleach) （像肥皂、小蘇打溶在水裡、漂白水）。Each whole step is a big jump 每差一整格就是一大跳：pH 3 is much more acid than pH 4 pH 3比pH 4酸得多。

Scientists use it, but so do pool cleaners, farmers, and people with fish tanks. You say it as two letters, 'p' 'H', never like the 'ph' in 'phone'. The H is the international sign for hydrogen; pH is about hydrogen ions in the mix.

Scientists use it 科學家會用它，but so do pool cleaners, farmers, and people with fish tanks 但清游泳池的人、農夫，還有養魚缸的人也會用。You say it as two letters, 'p' 'H' 唸的時候要唸成兩個字母，'p' 'H'，never like the 'ph' in 'phone' 絕對不要唸成'phone'裡的'ph'那個音。The H is the international sign for hydrogen H是氫的國際符號；pH is about hydrogen ions in the mix pH講的是這個混合物裡的氫離子。

The scale was introduced in 1909 by S. P. L. Sørensen, who spoke of a 'hydrogen ion exponent'. He may have chosen p as a simple label; others guess it came from words for 'power' (French puissance, German Potenz, Danish potens) or from 'potential'.

The scale was introduced in 1909 by S. P. L. Sørensen 這個量表是1909年由S. P. L. Sørensen提出的，who spoke of a 'hydrogen ion exponent' 他當時講的是「氫離子指數」。He may have chosen p as a simple label 他選p這個字母可能只是當作一個簡單的標籤；others guess it came from words for 'power' (French puissance, German Potenz, Danish potens) or from 'potential' 也有人猜是來自表示「力量」的字（法文puissance、德文Potenz、丹麥文potens），或是來自'potential'。

Though actually, in a serious lab the number can sit a little outside 0–14 when a mix is extremely strong — but the everyday scale you will be tested on is still that 0-to-14 line with 7 in the middle.

Though actually, in a serious lab 但其實在正式的實驗室裡，the number can sit a little outside 0–14 這個數字有時候會超出0到14一點點 when a mix is extremely strong 當一個混合物非常非常強的時候——but the everyday scale you will be tested on is still that 0-to-14 line with 7 in the middle 但你考試會考的日常量表，還是那條0到14、7在中間的線。