Sucrose and distilled water are safe and non-toxic. However, appropriate safety gear (lab coat, safety goggles, gloves) should be worn when preparing the solutions and performing the demonstration. Sodium hydroxide and potassium permanganate can cause irritation and chemical burns in contact with skin or mucous membranes. The chemical solutions must be labelled and kept away from children and pets to avoid accidental ingestion. Potassium permanganate is highly toxic to aquatic organisms. In some places, pouring a small quantity of a solution down the drain is allowed. The reader is advised to consult federal, state, and local regulations for proper disposal.
Envy_of_all_cats
I want my nav bar to be blue. It just looks better to me, but it doesn’t have to be that way for everyone. At least add an option where I can change it back to blue. Please. I do not like the purple. Thankyou.
Июнь 28, 2023 22:12:54
Crispydogs101
Nope. As it’s rejected
Zacharry wrote:
7.14 Revert the purple color palette back to blue
The specific color of purple was chosen as a practical one, as the Scratch Team determined through research that it is the color which is the most helpful for those with vision impairments. That is, the color change is important for the sake of improved accessibility, which means that more people will be able to use Scratch. For more information on the Scratch Team’s process that led to the purple color palette, see this post.
However, an option to customize the color palette is NOT rejected; you can discuss it on this topic.
Июнь 28, 2023 22:13:07
cs3868895
7.14 rejection
Za-Chary wrote:
7.14 Revert the purple color palette back to blue
The specific color of purple was chosen as a practical one, as the Scratch Team determined through research that it is the color which is the most helpful for those with vision impairments. That is, the color change is important for the sake of improved accessibility, which means that more people will be able to use Scratch. For more information on the Scratch Team’s process that led to the purple color palette, see this post.
However, an option to customize the color palette is NOT rejected; you can discuss it on this topic.
Июнь 28, 2023 22:33:01
Color Change Chameleon Materials
For this demonstration, you start by preparing two separate solutions:
Solution A
- 2 mg potassium permanganate
- 500 ml distilled water
Dissolve a small amount of potassium permanganate into water. The amount isn’t critical, but don’t use too much or else the solution will be too deeply colored to see the color changes. Use distilled water rather than tap water to avoid problems caused by salts in tap water that can affect water pH and interfere with the reaction. The solution should be a deep purple color.
Solution B
- 6 g sugar (sucrose)
- 10 g sodium hydroxide (NaOH)
- 750 ml distilled water
Dissolve the sugar and sodium hydroxide in the water. The reaction between sodium hydroxide and water is exothermic, so expect some heat to be produced. This will be a clear solution.
Make the Chameleon Change Colors
When you’re ready to start the demonstration, all you need to do is mix the two solutions together. You’ll get the most dramatic effect if you swirl the mixture together to thoroughly combine the reactants.
Upon mixing, the purple of the potassium permanganate solution immediately changes to blue. It changes to green fairly quickly, but it takes a few minutes for the next color change to pale orange-yellow, as manganese dioxide (MnO2) precipitates. If you let the solution sit long enough, the manganese dioxide will sink to the bottom of the flask, leaving you with a clear liquid.
Chemical Chameleon Redox Reaction
The color changes are the result oxidation and reduction or a redox reaction.
The potassium permanganate is reduced (gains electrons), while the sugar is oxidized (loses electrons). This occurs in two steps. First, the permanangate ion (purple in solution) is reduced to form the manganate ion (green in solution):
As the reaction is proceeding, both the purple permanganate and green manganate are present, blending together to produce a solution that appears blue. Eventually, there is more green manganate, yielding a green solution.
Next, the green manganate ion is further reduced and forms manganese dioxide:
Manganese dioxide is golden brown solid, but the particles are so small they make the solution appear to change color. Eventually, the particles will settle out of solution, leaving it clear.
The chameleon demonstration is just one of many possible color change chemistry experiments you can perform. If you don’t have the materials on hand for this particular demonstration, consider trying a different one.
Procedures for changing purple to blue
Brightness shifts all pixel values up or down the tonal range, lightening or darkening all colors equally.
Contrast adjusts the difference between light and dark colors.
Intensity brightens the light areas of the drawing or darkens the dark areas.
| To adjust the color balance |
| 1 . | Select a bitmap . |
| 2 . | Click Effects Adjust Color balance (or press Ctrl + Shift + B). |
| 3 . | Perform a task from the following table. |
Enable the Shadows, Midtones, and Highlights check boxes, respectively.
Enable the Preserve luminance check box.
Move the Cyan-Red slider to the left or right, respectively.
Move the Magenta-Green slider to the left or right, respectively.
Move the Yellow-Blue slider to the left or right, respectively.
| To apply the Gamma effect |
| 1 . | Select a bitmap . |
| 2 . | Click Effects Adjust Gamma. |
| 3 . | Move the Gamma value slider. |
| Higher values brighten midtones; lower values darken them. |
| To adjust hue, saturation, and lightness |
| 1 . | Select a bitmap . |
| 2 . | Click Effects Adjust Hue/saturation/lightness (or press Ctrl + Shift + U). |
| 3 . | Perform a task from the following table. |
Enable the Master option in the Channels area.
Enable the Red, Yellow, Green, Cyan, Blue, Magenta, or Grayscale option in the Channels area.
Move the Hue slider to redistribute the colors in an image.
Move the Saturation slider. A setting of -100 results in a grayscale image. A setting of 100 produces vibrant, unnatural colors.
Se the amount of white ( positive values) or black (negative values)
Move the Lightness slider.
| To replace colors |
| 1 . | Select a bitmap . |
| 2 . | Click Effects Adjust Replace colors. |
| 3 . | Click the Old color picker and choose the color that you want to replace. |
| Tip: You can pick color from the bitmap by clicking the Eyedropper tool , and clicking the image. |
| 4 . | Click the New color picker, and choose a replacement color. |
Move the Hue, Saturation, and Lightness sliders, respectively.
Enable the Ignore grayscale check box.
Note: Disabling the Ignore grayscale check box replaces gray pixels based on saturation and lightness values alone.
Move the Range slider.
Enable the Single destination check box.
| To apply the Sample/target balance effect |
| 1 . | Select a bitmap . |
| 2 . | Click Effects Adjust Sample/target balance. |
| 3 . | Choose a color channel from the Channel list box. |
| The color channels that appear in the Channel list box depend on the color mode of the bitmap. There is one composite channel and one channel for each color component. If you want to adjust all color channels, even when viewing only one channel, enable the Always adjust all channels check box. |
| 4 . | Click the Low-point , Mid-point , and High-point Eyedropper tool, and click in the image to choose a dark area, midtone area, and light area, respectively. |
| 5 . | Double-click the target color for the shadows, midtones, or highlights, and choose a new color. |
Enable the Clip automatically check box to set the range of the histogram display and ensure that all spikes fit on the chart. When the Clip automatically check box is disabled, use the Clipping box to set the percentage of brightness values that are ignored when identifying the light and dark colors in the histogram.
Not all suite components documented in this Help are available in our Trial, Academic, and OEM versions. Unavailable components may include Corel applications, product features, third-party utilities, and extra content files.
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