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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 31 May 2023 05:37 
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Некоторые продукты я люблю есть вприкуску с репчатым луком. Например, пельмени. Лук можно предварительно замариновать в столовом уксусе (vinegar), хотя бы минут 10 - 30, так вкуснее.
Попалась луковица с сиреневыми прожилками. И уксус окрасился в розовый цвет, не догадался сфотографировать.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 31 May 2023 09:24 
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У нас продавался репчатый лук фиолетового цвета, стоил он раза в полтора-два дороже, чем обычный. По вкусу - примерно такой же или более горький.

Продается ли сейчас - не знаю, поскольку лук из "еды для бедных" превратился в "деликатес для аристократов" - перестал обращать на него внимание.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 01 Jun 2023 06:14 
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Обычный репчатый лук (привозной) у нас не дороже картофеля.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 01 Jun 2023 13:28 
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Red horse-chestnut flowers in atmosphere of ammonia - pt.4
http://chemistry-chemists.com/N3_2023/C ... .html#1002
Quote:
The flowers of Red horse-chestnut were placed into an atmosphere of ammonia. The red flowers changed their color to pale grey-purple.

Unfortunately, the beautiful flowers lost their charm during the experiment.
Attachment:
Red_horse-chestnut_flowers_atmosphere_ammonia-1.jpg
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Red_horse-chestnut_flowers_atmosphere_ammonia-15.jpg
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Обычный репчатый лук (привозной) у нас не дороже картофеля.

У нас раньше было так же, а теперь подорожание лука репчатого стало интернет-мемом.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 03 Jun 2023 19:02 
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Robinia hispida flowers in atmosphere of ammonia - pt.5
http://chemistry-chemists.com/N3_2023/C ... .html#1003
Attachment:
Robinia_hispida_flowers_atmosphere_ammonia-19.jpg
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 07 Jun 2023 12:04 
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Symphytum asperum: pink and blue flowers - pt. 1a
http://chemistry-chemists.com/N3_2023/C ... html#10010
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 08 Jun 2023 15:22 
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Дополнил часть статьи, т.к. встретил еще одно аналогичное растение:

Symphytum asperum and Echium vulgare: pink flowers turn blue - pt. 1a
http://chemistry-chemists.com/N3_2023/C ... html#10010
Attachment:
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 15 Jun 2023 10:18 
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Strawberry, nitric acid, baking soda and ammonia (plant pigments colour change)
http://chemistry-chemists.com/N3_2023/C ... -P2-3.html
Quote:
After a series of experiments with flowers, we used berries for the same purpose: to demonstrate the colour changes of plant pigments as the result of pH changes.

Chopped strawberries were mixed with distilled water to obtain a suspension ("a pasta" - partial homogenization). The liquid was divided into three parts. A concentrated ammonia solution was added to the first part.

The red-orange liquid became dark, burgundy-brown. A saturated sodium bicarbonate solution was added to the second part of the strawberry suspension. The liquid turned burgundy (lighter than previous one). A concentrated nitric acid was added to the third part of the liquid. The liquid colour did not change.

An excess of concentrated nitric acid was added to the first and second parts of the liquid (to neutralize ammonia or sodium bicarbonate). Both liquids returned to their original red-orange colour.

I hope that the colour changes in the next experiments would be more beautiful.

Attachment:
Strawberry_nitric_acid_baking_soda_ammonia-2.jpg
Strawberry_nitric_acid_baking_soda_ammonia-2.jpg [ 374.99 KiB | Viewed 4958 times ]

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 15 Jun 2023 20:18 
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Чай каркадэ (гибискус).
Attachment:
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Добавлена серная кислота (электролит).
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Добавлен щелочь (крот).
Attachment:
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20230615_191203.jpg [ 750.16 KiB | Viewed 4947 times ]

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 15 Jun 2023 21:16 
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Каркаде я попробовать не догадался. Нужно будет выбрать момент, когда где-то зацветет гибискус.

Цветная шкала от универсальной индикаторной бумаги (последнее фото) - немного другое. В смысле, что гибискус даст один цвет, а универсальный индикатор - другой. В составе бумажки - сразу несколько индикаторов. Думаю, что для бумаги, шкала которой на фото:
Quote:
универсальный индикатор (по Богену) следующего состава: фенолфталеин (0,2 г), метиловый красный (0,4 г), диметиламинобензол (0,6 г), бромтимоловый синий (0,8 г), тимоловый синий (1,0 г), спирт этиловый (1 л), гидроксид натрия (до появления желтой окраски).

Есть и другое рецепты состава универсального индикатора.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 14 Jul 2023 14:30 
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Red onion, ammonia, nitric acid and acetic acid - pt.7
http://chemistry-chemists.com/N3_2023/C ... .html#1002
Attachment:
Onion-Red-1.jpg
Onion-Red-1.jpg [ 91.99 KiB | Viewed 4688 times ]

Quote:
Red onions (also known as purple onions) are often used in cooking, but for our purpose the most interesting thing is their colour. The violet epiderma is loaded with anthocyanins which give them their colour. Anthocyanins can change their colours at different pH values of the solution, for example, after adding of ammonia or hydrochloric acid.

In the first experiment three pieces of freshy scales (leaf bases) of a red onion were placed in three beakers. A concentrated aqueous ammonia was added in the first beaker, tap water was added in the second beaker (control sample) and concentrated nitric acid was added into the third.

In the ammonia solution, violet surface of the freshy scale of the onion turned green and then yellow, but this process was slow and occurred only at the radge of the piece (also in the places where the surface was mechanically damaged). The ammonia solution became green then yellow. Green colour is explained by changing of pH (the plant dye behaves an acid-base indicator). Such colour change is reversible (if excess of an acid is added to lower pH, the colour will turn).

But I think that the yellow colour is the result of an oxidation of the plant dye by air oxygen in alkaline medium. Adding of an excess of nitric acid did not change the yellow colour of the solution (therefore, the dye lost its properties of an acid-base indicator).

In the nitric acid, violet surface of the onion became red, the solution itself turned brown. The colour change was also slow.

In tap water, violet surface of the onion did not change.

In all cases, the diffusion of chemicals into the plant tissue was rather slow. Therefore, the conditions of the experiment were changed. A thin violet epiderma was separated from freshy scales of the onion. These thin violet films were used in the following experiments.

The violet films turned green very quickly - even in an atmosphere of an ammonia vapours. Of course, the ammonia solution caused the same effect. Glacial acetic acid was added to the green films - as quickly as possible. The films and the solution became red/pink. In this case the plant dye behaved as a reverse acid-base indicator.

When the violet films were placed into concentrated nitric acid, the colour of the films and the solution turned brown (probably, a destruction of the dye took place).
Attachment:
Red_onion_ammonia_acetic_acid-14.jpg
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 19 Jul 2023 09:32 
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Salvia Splendens (''Red Salvia'') flowers, ammonia and hydrochloric acid - pt.8
http://chemistry-chemists.com/N3_2023/C ... -P2-4.html
Attachment:
Salvia_splendens-2.jpg
Salvia_splendens-2.jpg [ 968.62 KiB | Viewed 4560 times ]

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In Ukraine, a bright red flowering plant is grown in flower beds. This flower is very common in our country as an ornamental plant. We call this plant "Chervona sal'viya" ("Red Salvia"), the biological name is Salvia Splendens. This species is native to Brazil but is grown in many other countries.

Salvia Splendens plants are usually grown in large groups, many bright red flowers look very beautiful - like a fire. Many years ago, I saw Salvia Splendens plants with dark blue flowers (maybe they were dark purple - I can't remember). Such plants of Salvia Splendens with dark blue flowers (instead of red ones) were very rarely found in our flower beds.

The red flowers of Salvia Splendens can be used for chemical experiments with plant dyes. The pigment(s) in these flowers is probably an acid-base indicator. Perhaps, the bright red colour will turn dark blue or dark purple in an atmosphere of ammonia? (I guess so, because there are Salvia Splendens plants with flowers of such colours).

A small amount of concentrated ammonia solution was poured in a glass. The red flowers were placed in the glass (suspended above the level of the solution). The red flowers of Salvia Splendens gradually turned dark purple.

Then these dark purple flowers (after the treatment with ammonia) were placed in an atmosphere of hydrochloric acid vapours. A thick smoke of ammonium chloride immediately formed. The dark purple flowers turned red. But this process was slow, the flowers were doused by hydrochloric acid to speed up the colour transformation. The plant tissues of the flowers were partially destructed by the strong acid.

Attachment:
salvia_splendens_ammonia-16.jpg
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 24 Jul 2023 09:32 
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Смотрел английский словарь (именно словарь - не энциклопедию или справочник). Один из двух примеров к слову dissolve был таким:
Quote:
Nitric acid will dissolve most animal tissue.

Азотная кислота растворяет (будет растворять) большинство животных тканей.

Рандомный пример оказался очень актуальным: азотная или соляная кислоты разрушают цветы (растительные ткани) во время экспериментов по изменению окраски.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 28 Jul 2023 11:25 
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Ageratum Houstonianum: flowers become like green moss - pt.10
http://chemistry-chemists.com/N3_2023/C ... -P2-5.html
Quote:
Ageratum Houstonianum is an ornamental plant which is widely grown in flower beds and gardens. The violet flowers of this plant were used for the next experiments.

An ammonia solution was poured into the bottom of a glass, the flowers was placed in the glass. In an atmosphere of ammonia, the violet flowers became grey, then green. As a result, an inflorescence looked like green moss.

The green flowers were placed in the new glass, then glacial acetic acid was added. The colour gradually changed to violet, then to pink and, finally - to pink-orange.

New violet flowers of Ageratum Houstonianum were placed into the same beaker with glacial acetic acid. The flowers turned pink, then they turned pink-orange.

After that, the flowers of Ageratum Houstonianum were being completely immersed into glacial acetic acid for 1 hour. The pink-orange solution was formed. This solution was used for the next experiment.

A concentrated ammonia solution was gradually added to the solution of the plant dye (in acetic acid). Fist, the pink-orange solution turned colourless then it became a bright greenish-yellow colour (final pH was 9-10). Then concentrated hydrochloric acid was slowly added. The bright greenish-yellow solution first turned pale yellow then turned pale orange (unfortunately, during our experiment, the solution was diluted, so all colours turned pale). The final pH was <=1.

Attachment:
Ageratum_houstonianum_flowers_become_moss-6.jpg
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 29 Jul 2023 05:17 
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Когда осенью листья становятся жёлтыми и оранжевыми, это не значит, что хлорофилл меняет цвет. Хлорофилл разрушается и другие красители становятся видимыми.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 29 Jul 2023 09:56 
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Не просто становятся видимыми - активируется их синтез.

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 02 Aug 2023 11:44 
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Hibiscus Syriacus flowers, ammonia and acetic acid - pt.11
http://chemistry-chemists.com/N3_2023/C ... .html#1002
Attachment:
Hibiscus_syriacus-14.jpg
Hibiscus_syriacus-14.jpg [ 285.64 KiB | Viewed 4027 times ]
Attachment:
Hibiscus_syriacus_ammonia_acetic_acid-10.jpg
Hibiscus_syriacus_ammonia_acetic_acid-10.jpg [ 345.07 KiB | Viewed 4027 times ]

Quote:
A few years ago, bushes (or small trees) with large, beautiful flowers appeared in our parks and gardens. The colour of the flowers was different, but the shape was similar. I wonder... What kind of plant is this? I photographed the plant and posted photos on the chemical forum. A colleague suggested that this is Hibiscus Syriacus.

The homeland of the plant is Asia (as you might guess from the name). It grows in China, Korea and Western Asia. A hardy plant with high tolerance to heat, drought, poor soils and air pollution (ideal for cities). The colours of the flowers of Hibiscus Syriacus vary widely, with petals ranging from white to bright red depending on the cultivar. The shape of the flower may also differ from the usual one (no one cancelled the selection).

Thanks to its beautiful flowers, Hibiscus Syriacus is grown as an ornamental plant far beyond its natural range. In particular, on the open ground (not in a greenhouse) they began to cultivate it in the south of Ukraine and in Moldova. It is interesting that I saw Hibiscus Syriacus in Kyiv, and this is already the north of Ukraine. Even without referring to the literature, one can guess that the southern plant is unlikely to be resistant to frost, but the climate is changing - winters are getting warmer. The tree shown in the photographs below has been growing for several years and no one covered it for the winter...

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 02 Aug 2023 18:39 
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Upd.
After the experiment I went back to the Hibiscus Syriacus tree to take some better photos. Suddenly I saw that my previous observations were not accurate. During all time of flowing, the petals of the flowers are pink. The pink petals turn blue as the flowers are fading (but when the buds are opening, the petals are pink not blue). Fortunately, it does not change general conclusions: the pH change in tissue leads to the change of the colour of the plant dye. And at this time, the flowers are on the tree, not in the beaker (with ammonia).

Upd.
После эксперимента я вернулся к дереву Hibiscus Syriacus, чтобы сделать несколько фотографий получше. Внезапно увидел, что мои предыдущие наблюдения были неточными. Все время цветения лепестки цветков розовые (не синие). Розовые лепестки становятся частично синими, когда цветы увядают (зато когда бутоны раскрываются, лепестки розовые, а не синие). К счастью, это не меняет общих выводов: изменение рН в растительной ткани приводит к изменению окраски растительного красителя. И в это время цветок находится на дереве, а не в химическом стакане (с аммиаком).

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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 10 Aug 2023 10:40 
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Tagetes flower and ammonia - p.12
http://chemistry-chemists.com/N3_2023/C ... -P2-6.html
Attachment:
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 Post subject: Re: Цветочки и химия... (опыты с растениями и насекомыми)
PostPosted: 10 Aug 2023 19:56 
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Впервые слышу, чтобы этот цветок использовали в качестве приправы. У него довольно сильный запах.


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