CRITERION D: REFLECTING ON THE IMPACTS OF SCIENCE
化学作业代写 A pH indicator measures whether a substance (usually a liquid) is acidic or basic, and some indicators can also measure how acidic…
Red Cabbage pH Indicator
自制紫甘蓝酸碱指示剂
Introduction: 化学作业代写
A pH indicator measures whether a substance (usually a liquid) is acidic or basic, and some indicators can also measure how acidic or basic it is. When the indicator comes in contact with a substance, the indicator’s color corresponds to that substance’s approximate pH, which is a scale of zero to fourteen (with zero being the most acidic, seven being neutral, and fourteen being the most basic) that indicates the acidity or basicity of a substance.
不同的指示剂在不同的酸碱环境下呈现不同的颜色。通过这些颜色的变化我们还可以判断所测样品酸度和碱度。pH指示剂的变色范围一般从1~14, pH值越小，酸性越强，pH越大，碱性越大。
Red Cabbage pH Indicator Colors 紫甘蓝酸碱指示剂变色情况
| pH | 2 | 4 | 6 | 8 | 10 | 12 |
| Color | Red | Purple | Violet | Blue | Blue-Green | Greenish Yellow |
Aim： 化学作业代写
Make an indicator solution from the leaves of a red cabbage (also called purple cabbage) by following the simple process and test the approximate pH of some common household liquids. [Note: A solution in this sense simply means a substance dissolved in water. In this case, the chemicals with indicator properties in the cabbage leaves are dissolved in boiling water.
利用紫甘蓝自制酸碱指示剂，检验家中常用液体的pH值。
Hypothesis:
Predict acidity and basicity of those common household solution before your investigation.
根据常识，在实验前猜测常见液体的酸碱性
Materials: 化学作业代写
red cabbage (half)
blender and gauze / a knife
tap water (with the amount that just cover the cabbage)
baking soda (mix 1 teaspoon with 1 tablespoon of water )
white vinegar
orange juice/apple juice/lemon juice
cola
coffee or tea
milk
dish soap（1茶匙洗洁精与1汤匙水混合-不必精确）
soda water
containers for testing holding cabbage solution 盛装紫甘蓝浸出液和检测样品的容器
Methods:
Chop half a cabbage into small pieces. Put the pieces in the saucepan and cover with water.
Heat the pan on the stove until the water begins to boil, then turn the heat to low and let the cabbage simmer for 20 minutes. Stir [Caution: HOT!]
(Alternatively, you can place chopped cabbage in a blender, cover it with boiling water, and blend it.)
将半个紫甘蓝切成小块，放入锅中，加水直到刚好没过紫甘蓝。加热直至沸腾，小火继续加热20分钟，同时不断搅拌。【注意：加热时注意安全】（另
外，也可使用榨汁机，榨汁时加水）
The water in the pan should now appear dark purple or dark blue, depending on the pH of the water (tap water tends to be slightly basic, so if you used tap water, your solution may be bluish).The leaves should also appear less purple, with a more bluish green color. If the watercolor has not changed, try boiling it a bit longer. Let thecooked cabbage cool slightly. Collect the purplish cabbage liquid in a container. This is the finished indicator solution. [Caution: Make sure to clean up any drips because the cabbage liquid can stain.] 化学作业代写
停止加热后，锅内液体的颜色是深蓝或者深紫。颜色的不同取决于使用水的酸碱性。如果使用自来水，溶液的颜色应是浅蓝，因为自来水略显碱性。紫甘蓝叶片原来的紫色明显变浅。如果水的颜色没太大变化，再次煮沸。待冷却至室温后，转移紫甘蓝浸出液至容器中。【注意：紫甘蓝会沾染到衣物上】
Mix 3 ml (Don’t have to be exact.) of the above cabbage indicator solution with same amount of each household liquids in separate containers. Observe color changes and take photos.
[Caution: Test samples in separate containers]
在不同容器中，分别将3 ml（不必精确）紫甘蓝浸出液与相同体积的家用常见液体混合。观察颜色变化，同时拍照记录。【注意：不同检测分别在不同的容器中进行，切勿混合】
