水溶液って実は身のまわりにたくさんあるよ！食塩水やジュース、お茶なんかも全部水溶液なんだ。今回は水溶液の基本的な性質と濃度の計算方法を覚えて、テストで確実に点数を取れるようになろう。
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Updated Mar 31, 2026
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水溶液の基本とその性質を学ぼう
1 / 6
水溶液の基本と重要用語
君が毎日飲んでるジュースや、料理で使う食塩水、これらは全て水溶液だよ。水溶液は物質が水に溶けて全体が均一になった液体のことで、透明で時間がたっても沈殿しないのが特徴なんだ。
水溶液を理解するには、まず3つの用語を完璧に覚えよう。溶質は溶けている物質（食塩水なら食塩）、溶媒は物質を溶かしている液体（水）、溶液は溶質が溶媒に溶けてできた液体全体（食塩水）のことだ。
溶媒が水以外の場合もあるけど、中学では基本的に水溶液を扱うから安心して。この3つの言葉の関係をしっかり理解しておけば、後の計算問題もスムーズに解けるようになるよ。
💡 覚えるコツ: 「溶質→溶けてる質（もの）」「溶媒→溶かす媒体」「溶液→全体の液体」と覚えよう！
溶解の仕組みと水溶液の性質
物質が水に溶ける現象を溶解って呼ぶんだ。溶質は水の中でとても小さな粒子（原子や分子）になって、水分子の間に均一に広がるから、水溶液は透明に見えるんだよ。
だからこそ、水溶液には大事な特徴がある。まず透明であること、そして全体が均一（どこをとっても濃さが同じ）であること。さらに時間がたっても溶けている物質は沈殿しないし、ろ紙でこしても溶質を取り出すことはできないんだ。
この性質は、砂と水を混ぜた濁った液体とは全く違う。砂水は時間がたつと砂が沈むし、ろ過すれば砂を取り出せるからね。
💡 実験のイメージ: コーヒーフィルターで食塩水をこしても、食塩は取れないよね！
質量パーセント濃度の計算
水溶液の「こさ」を表すのが濃度で、テストでは計算問題がよく出るから絶対にマスターしよう。質量パーセント濃度は、溶液全体の質量のうち溶質がどれくらいの割合を占めているかを%で表したものだ。
公式はこれ：濃度[%] = (溶質の質量 ÷ 溶液の質量) × 100。ここで超重要なのは、分母が「溶液の質量」であることだよ。溶液の質量 = 溶質の質量 + 溶媒の質量だから、水の質量だけを使っちゃダメ！
例えば食塩20gを水80gに溶かした場合：溶液の質量は20g + 80g = 100g、濃度は(20g ÷ 100g) × 100 = 20%になる。この計算パターンをしっかり覚えておこう。
💡 よくある間違い: 分母を「水の質量（80g）」にしちゃうミス。必ず「溶液の質量（100g）」を使おう！
濃度計算の実践と逆算
濃度がわかっている場合の逆算もできるようになろう。15%の砂糖水200gがあるとき、砂糖の質量は 200g × (15/100) = 30g、水の質量は 200g - 30g = 170gって計算できるんだ。
飽和水溶液も重要な概念だよ。これは、ある温度でそれ以上溶質が溶けなくなった状態の水溶液のこと。砂糖を水にどんどん入れていって、もう溶けなくなったときの上澄み液が飽和水溶液なんだ。
溶解度は100gの水に溶ける溶質の最大質量のことで、物質の種類と温度によって決まる。一般的に固体は温度が高いほどたくさん溶けるから、熱いお茶には砂糖がよく溶けるよね。
💡 計算のコツ: 問題文で「溶質」「溶媒」「溶液」のどれを聞かれているか、まず確認しよう！
テスト対策と重要ポイント
テストで点数を落とさないための最重要ポイントを確認しよう。濃度計算では分母を溶液の質量（溶質+溶媒）にすること、これが一番多い間違いだから絶対に注意して！
用語の定義も正確に覚えておこう。特に「溶液」と「水溶液」の違い（溶媒が水なら水溶液）は頻出だよ。水溶液の性質（透明・均一・沈殿しない・ろ過できない）も説明できるようにしておこう。
温度と溶解度の関係も重要で、固体の溶解度は温度が高くなると大きくなるのが普通。この性質を利用したのが再結晶という方法で、一度溶かしたものを冷やして再び結晶として取り出すんだ。
💡 最終チェック: 溶質・溶媒・溶液の区別、濃度の公式、水溶液の4つの性質を言えればOK！
要点まとめ
試験前にはこれだけ確認すれば大丈夫！溶質は溶けているもの（塩など）、溶媒は溶かしている液体（水）、溶液は全体（食塩水）のこと。
濃度の計算式は「(溶質 ÷ 溶液) × 100」で、溶液の質量 = 溶質の質量 + 溶媒の質量だったよね。そして水溶液は透明で均一、ろ過できないという性質を持っている。
これらのポイントをしっかり押さえて、計算問題では落ち着いて公式に当てはめれば必ず解けるよ。君なら絶対にできる！
💡 最後の確認: 公式を声に出して3回言ってみよう。体で覚えることが大切だよ！
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content in 化学
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
水溶液の基本とその性質を学ぼう
水溶液って実は身のまわりにたくさんあるよ！食塩水やジュース、お茶なんかも全部水溶液なんだ。今回は水溶液の基本的な性質と濃度の計算方法を覚えて、テストで確実に点数を取れるようになろう。
水溶液の基本と重要用語
君が毎日飲んでるジュースや、料理で使う食塩水、これらは全て水溶液だよ。水溶液は物質が水に溶けて全体が均一になった液体のことで、透明で時間がたっても沈殿しないのが特徴なんだ。
水溶液を理解するには、まず3つの用語を完璧に覚えよう。溶質は溶けている物質（食塩水なら食塩）、溶媒は物質を溶かしている液体（水）、溶液は溶質が溶媒に溶けてできた液体全体（食塩水）のことだ。
溶媒が水以外の場合もあるけど、中学では基本的に水溶液を扱うから安心して。この3つの言葉の関係をしっかり理解しておけば、後の計算問題もスムーズに解けるようになるよ。
💡 覚えるコツ: 「溶質→溶けてる質（もの）」「溶媒→溶かす媒体」「溶液→全体の液体」と覚えよう！
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
溶解の仕組みと水溶液の性質
物質が水に溶ける現象を溶解って呼ぶんだ。溶質は水の中でとても小さな粒子（原子や分子）になって、水分子の間に均一に広がるから、水溶液は透明に見えるんだよ。
だからこそ、水溶液には大事な特徴がある。まず透明であること、そして全体が均一（どこをとっても濃さが同じ）であること。さらに時間がたっても溶けている物質は沈殿しないし、ろ紙でこしても溶質を取り出すことはできないんだ。
この性質は、砂と水を混ぜた濁った液体とは全く違う。砂水は時間がたつと砂が沈むし、ろ過すれば砂を取り出せるからね。
💡 実験のイメージ: コーヒーフィルターで食塩水をこしても、食塩は取れないよね！
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
質量パーセント濃度の計算
水溶液の「こさ」を表すのが濃度で、テストでは計算問題がよく出るから絶対にマスターしよう。質量パーセント濃度は、溶液全体の質量のうち溶質がどれくらいの割合を占めているかを%で表したものだ。
公式はこれ：濃度[%] = (溶質の質量 ÷ 溶液の質量) × 100。ここで超重要なのは、分母が「溶液の質量」であることだよ。溶液の質量 = 溶質の質量 + 溶媒の質量だから、水の質量だけを使っちゃダメ！
例えば食塩20gを水80gに溶かした場合：溶液の質量は20g + 80g = 100g、濃度は(20g ÷ 100g) × 100 = 20%になる。この計算パターンをしっかり覚えておこう。
💡 よくある間違い: 分母を「水の質量（80g）」にしちゃうミス。必ず「溶液の質量（100g）」を使おう！
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
濃度計算の実践と逆算
濃度がわかっている場合の逆算もできるようになろう。15%の砂糖水200gがあるとき、砂糖の質量は 200g × (15/100) = 30g、水の質量は 200g - 30g = 170gって計算できるんだ。
飽和水溶液も重要な概念だよ。これは、ある温度でそれ以上溶質が溶けなくなった状態の水溶液のこと。砂糖を水にどんどん入れていって、もう溶けなくなったときの上澄み液が飽和水溶液なんだ。
溶解度は100gの水に溶ける溶質の最大質量のことで、物質の種類と温度によって決まる。一般的に固体は温度が高いほどたくさん溶けるから、熱いお茶には砂糖がよく溶けるよね。
💡 計算のコツ: 問題文で「溶質」「溶媒」「溶液」のどれを聞かれているか、まず確認しよう！
Sign up to see the contentIt's free!
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Join milions of students
テスト対策と重要ポイント
テストで点数を落とさないための最重要ポイントを確認しよう。濃度計算では分母を溶液の質量（溶質+溶媒）にすること、これが一番多い間違いだから絶対に注意して！
用語の定義も正確に覚えておこう。特に「溶液」と「水溶液」の違い（溶媒が水なら水溶液）は頻出だよ。水溶液の性質（透明・均一・沈殿しない・ろ過できない）も説明できるようにしておこう。
温度と溶解度の関係も重要で、固体の溶解度は温度が高くなると大きくなるのが普通。この性質を利用したのが再結晶という方法で、一度溶かしたものを冷やして再び結晶として取り出すんだ。
💡 最終チェック: 溶質・溶媒・溶液の区別、濃度の公式、水溶液の4つの性質を言えればOK！
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
要点まとめ
試験前にはこれだけ確認すれば大丈夫！溶質は溶けているもの（塩など）、溶媒は溶かしている液体（水）、溶液は全体（食塩水）のこと。
濃度の計算式は「(溶質 ÷ 溶液) × 100」で、溶液の質量 = 溶質の質量 + 溶媒の質量だったよね。そして水溶液は透明で均一、ろ過できないという性質を持っている。
これらのポイントをしっかり押さえて、計算問題では落ち着いて公式に当てはめれば必ず解けるよ。君なら絶対にできる！
💡 最後の確認: 公式を声に出して3回言ってみよう。体で覚えることが大切だよ！
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Most popular content in 化学
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Students love us — and so will you.
4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user