化学で必須の溶液の濃度について学ぼう！実験や化学反応の計算で絶対に使うから、しっかりマスターしておく必要がある。特にモル濃度は高校化学の基礎中の基礎だよ。
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Updated Mar 18, 2026
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溶液の濃度とは？基本の種類と計算方法
1 / 6
溶液の濃度の基本
溶液の濃度って、簡単に言うと「どのくらい濃いか」を数字で表したもの。化学反応の計算や実験の準備で毎回使うから、計算方法をマスターしないとダメなんだ。
まず基本的な用語を覚えよう。溶質は溶けている物質（食塩水なら食塩）、溶媒は溶かしている液体（食塩水なら水）、溶液は全体のこと。つまり溶液＝溶質＋溶媒っていう関係は絶対に覚えておこう！
ポイント: 溶液、溶質、溶媒の違いを混同しないこと。これが計算ミスの一番の原因だよ。
質量パーセント濃度
中学校でも習った質量パーセント濃度から復習しよう。これは溶液の質量に対する溶質の質量の割合で、単位は%だ。
計算式は 質量パーセント濃度[%] = (溶質の質量[g] ÷ 溶液の質量[g]) × 100 。ここで注意なのは、分母が「溶液」の質量だということ！溶媒の質量じゃないからね。
この濃度の特徴は、温度が変わっても値が変化しないこと。質量は温度で変わらないからね。ただし、化学反応の計算には向いていない。
モル濃度
高校化学で一番重要なモル濃度について学ぼう。これは溶液1Lあたりに含まれる溶質の**物質量（mol）**で表す濃度で、単位はmol/Lだ。
計算式は モル濃度 = 溶質の物質量[mol] ÷ 溶液の体積[L] 。ここで超重要なのは、分母が溶液の「体積」で、単位は必ずL（リットル）に変換すること！mLのままだと1000倍違う答えになっちゃう。
モル濃度の最大のメリットは、化学反応の量的関係の計算にめちゃくちゃ便利なこと。溶液の体積を測るだけで、そこに含まれる溶質の物質量がすぐわかる。
注意: 温度によって溶液の体積が変化するので、モル濃度の値も少し変わる。これが質量パーセント濃度との違いだ。
計算練習①：質量パーセント濃度
実際に問題を解いてみよう。質量パーセント濃度20%の塩化ナトリウム水溶液500gに含まれるNaClと水の質量を求める問題だ。
まず溶質の質量を計算する。20% = x[g] ÷ 500[g] × 100 これを解くと、x = 500 × 20/100 = 100g。だから塩化ナトリウムは100g。
次に水の質量は、溶液の質量から溶質の質量を引く。水の質量 = 500g - 100g = 400g。つまり水は400gだね。
計算練習②：モル濃度
今度はモル濃度の計算だ。NaOH 20gを水に溶かして500mLにした水溶液のモル濃度を求めよう。
まずNaOHの式量を計算：Na(23) + O(16) + H(1.0) = 40。だからモル質量は40 g/mol。
次にNaOH 20gの物質量：20g ÷ 40 g/mol = 0.50mol。溶液の体積を500mL = 0.500Lに変換。
最後にモル濃度を計算：0.50mol ÷ 0.500L = 1.0 mol/L。
計算のコツ: 単位の変換を忘れないこと！特にmLをLに直すのを忘れがち。
試験対策とまとめ
試験でよくある間違いを避けるポイントを覚えよう。単位の変換を忘れない（特に体積はL）、溶液と溶媒を混同しない（質量パーセント濃度の分母は溶液の質量）ことが重要だ。
希釈の計算では、溶質の物質量は変化しないという原理を使う。C₁V₁ = C₂V₂の関係式は超便利だから覚えておこう。
化学反応の計算ではモル濃度が基本になる。質量パーセント濃度よりもモル濃度の計算に慣れておくことが大切だよ。
最重要ポイント: 溶液 = 溶質 + 溶媒、そしてモル濃度の計算では必ず体積をLに変換！
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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
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Best app on earth! no words because it’s too good
Thomas R
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Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
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This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
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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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
溶液の濃度とは？基本の種類と計算方法
化学で必須の溶液の濃度について学ぼう！実験や化学反応の計算で絶対に使うから、しっかりマスターしておく必要がある。特にモル濃度は高校化学の基礎中の基礎だよ。
溶液の濃度の基本
溶液の濃度って、簡単に言うと「どのくらい濃いか」を数字で表したもの。化学反応の計算や実験の準備で毎回使うから、計算方法をマスターしないとダメなんだ。
まず基本的な用語を覚えよう。溶質は溶けている物質（食塩水なら食塩）、溶媒は溶かしている液体（食塩水なら水）、溶液は全体のこと。つまり溶液＝溶質＋溶媒っていう関係は絶対に覚えておこう！
ポイント: 溶液、溶質、溶媒の違いを混同しないこと。これが計算ミスの一番の原因だよ。
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質量パーセント濃度
中学校でも習った質量パーセント濃度から復習しよう。これは溶液の質量に対する溶質の質量の割合で、単位は%だ。
計算式は 質量パーセント濃度[%] = (溶質の質量[g] ÷ 溶液の質量[g]) × 100 。ここで注意なのは、分母が「溶液」の質量だということ！溶媒の質量じゃないからね。
この濃度の特徴は、温度が変わっても値が変化しないこと。質量は温度で変わらないからね。ただし、化学反応の計算には向いていない。
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モル濃度
高校化学で一番重要なモル濃度について学ぼう。これは溶液1Lあたりに含まれる溶質の**物質量（mol）**で表す濃度で、単位はmol/Lだ。
計算式は モル濃度 = 溶質の物質量[mol] ÷ 溶液の体積[L] 。ここで超重要なのは、分母が溶液の「体積」で、単位は必ずL（リットル）に変換すること！mLのままだと1000倍違う答えになっちゃう。
モル濃度の最大のメリットは、化学反応の量的関係の計算にめちゃくちゃ便利なこと。溶液の体積を測るだけで、そこに含まれる溶質の物質量がすぐわかる。
注意: 温度によって溶液の体積が変化するので、モル濃度の値も少し変わる。これが質量パーセント濃度との違いだ。
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計算練習①：質量パーセント濃度
実際に問題を解いてみよう。質量パーセント濃度20%の塩化ナトリウム水溶液500gに含まれるNaClと水の質量を求める問題だ。
まず溶質の質量を計算する。20% = x[g] ÷ 500[g] × 100 これを解くと、x = 500 × 20/100 = 100g。だから塩化ナトリウムは100g。
次に水の質量は、溶液の質量から溶質の質量を引く。水の質量 = 500g - 100g = 400g。つまり水は400gだね。
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計算練習②：モル濃度
今度はモル濃度の計算だ。NaOH 20gを水に溶かして500mLにした水溶液のモル濃度を求めよう。
まずNaOHの式量を計算：Na(23) + O(16) + H(1.0) = 40。だからモル質量は40 g/mol。
次にNaOH 20gの物質量：20g ÷ 40 g/mol = 0.50mol。溶液の体積を500mL = 0.500Lに変換。
最後にモル濃度を計算：0.50mol ÷ 0.500L = 1.0 mol/L。
計算のコツ: 単位の変換を忘れないこと！特にmLをLに直すのを忘れがち。
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試験対策とまとめ
試験でよくある間違いを避けるポイントを覚えよう。単位の変換を忘れない（特に体積はL）、溶液と溶媒を混同しない（質量パーセント濃度の分母は溶液の質量）ことが重要だ。
希釈の計算では、溶質の物質量は変化しないという原理を使う。C₁V₁ = C₂V₂の関係式は超便利だから覚えておこう。
化学反応の計算ではモル濃度が基本になる。質量パーセント濃度よりもモル濃度の計算に慣れておくことが大切だよ。
最重要ポイント: 溶液 = 溶質 + 溶媒、そしてモル濃度の計算では必ず体積をLに変換！
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and 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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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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user