Make Your Own pH Indicator with Chemist Dr. Sophia Tran!
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Page 1 Make Your Own pH Indicator with Chemist Dr. Sophia Tran! Supplies: Beakers (alternative: small plastic cups, one for each household material to be tested) Pipets (alternatives: spoon, eyedropper, or straw; for straw, place finger over top end of straw to hold liquid) Graduated cylinder with 5 mL measurement (alternatives: dosage cup from cough or cold medicine or 1 teaspoon measuring spoon) Head of red cabbage Knife and cutting board Pot, colander, water, and stove top Jar with lid (to store cabbage indicator, as needed) Household materials to test: baking soda, hand soap, lemon juice, vinegar, tap water, clear soda Explanation: The pH scale tells us if something is acidic, neutral, or basic. The pH scale runs from 0 to 14. If something measures lower than 7, it is acidic. If it is higher than 7, it is basic. If it is 7, it is neutral: neither acidic or basic. Understanding the pH of a chemical is important in everyday activities like cooking and gardening, the functions of our bodies, and many other things! Acids are usually very tart (like lemon juice) and bases are usually bitter (ever get some shampoo in your mouth on accident? Soap is basic!). If you add equal parts acid and base together they will actually neutralize each other! If something is too acidic or basic, it can damage or kill other things, like plants. Activity Instructions: Make a pH Indictor from Red Cabbage and Test pH of Household Material: Ask an adult for help with the knife, stove, and boiling water! 1) Use the cutting board and the knife to chop roughly a head of red cabbage. Place the pieces in your pot, add water so cabbage pieces are submerged, heat on stove, and boil for 5 minutes. Use colander to strain out the cabbage pieces and collect the liquid in jar. This liquid is the “cabbage indicator.” Let the cabbage indicator cool before use. While the cabbage indicator cools, complete “prediction” column in the experiment chart on page 2. 2) Pour about 5 mL of cabbage indicator in a beaker or plastic cup. Use the pipet to add a few drops of the household material you are testing to the cabbage indicator. Tip: If the household material is a solid, dissolve it in a little bit of water before adding it to the cabbage indicator. 3) Record the color change in the “observation” column on the Experiment Chart. Be sure to write it in the correct row for the material you tested. Then use the provided Color Change Chart on page 2 to determine if the household material you tested is an acid or a base. 4) Find some other household materials not listed on the Experiment Chart to test! Be sure to check with your parents before you test them! 5) Take one of the acids and one of the bases from the worksheet. Add equal amounts of the acid and base in a beaker or plastic cup then test the pH of the resulting mixture. Were you able to neutralize the chemicals? If you have leftover cabbage indicator, store it in the lidded jar and place it in the refrigerator. It will keep for two weeks!
Transcript of Make Your Own pH Indicator with Chemist Dr. Sophia Tran!
Page 1
Make Your Own pH Indicator with Chemist Dr. Sophia Tran!
Supplies:
Beakers (alternative: small plastic cups, one for each household material to be tested)
Pipets (alternatives: spoon, eyedropper, or straw; for straw, place finger over top end of straw to hold liquid)
Graduated cylinder with 5 mL measurement (alternatives: dosage cup from cough or cold medicine or 1 teaspoon measuring spoon)
Head of red cabbage
Knife and cutting board
Pot, colander, water, and stove top
Jar with lid (to store cabbage indicator, as needed)
Household materials to test: baking soda, hand soap, lemon juice, vinegar, tap water, clear soda
Explanation: The pH scale tells us if something is acidic, neutral, or basic. The pH scale runs from 0 to 14. If something measures lower than 7, it is acidic. If it is higher than 7, it is basic. If it is 7, it is neutral: neither acidic or basic. Understanding the pH of a chemical is important in everyday activities like cooking and gardening, the functions of our bodies, and many other things! Acids are usually very tart (like lemon juice) and bases are usually bitter (ever get some shampoo in your mouth on accident? Soap is basic!). If you add equal parts acid and base together they will actually neutralize each other! If something is too acidic or basic, it can damage or kill other things, like plants. Activity Instructions: Make a pH Indictor from Red Cabbage and Test pH of Household Material: Ask an adult for help with the knife, stove, and boiling water!
1) Use the cutting board and the knife to chop roughly a head of red cabbage. Place the pieces in your pot, add water so cabbage pieces are submerged, heat on stove, and boil for 5 minutes. Use colander to strain out the cabbage pieces and collect the liquid in jar. This liquid is the “cabbage indicator.” Let the cabbage indicator cool before use. While the cabbage indicator cools, complete “prediction” column in the experiment chart on page 2.
2) Pour about 5 mL of cabbage indicator in a beaker or plastic cup. Use the pipet to add a few drops of the household material you are testing to the cabbage indicator. Tip: If the household material is a solid, dissolve it in a little bit of water before adding it to the cabbage indicator.
3) Record the color change in the “observation” column on the Experiment Chart. Be sure to write it in the correct
row for the material you tested. Then use the provided Color Change Chart on page 2 to determine if the household material you tested is an acid or a base.
4) Find some other household materials not listed on the Experiment Chart to test! Be sure to check with your
parents before you test them!
5) Take one of the acids and one of the bases from the worksheet. Add equal amounts of the acid and base in a beaker or plastic cup then test the pH of the resulting mixture. Were you able to neutralize the chemicals?
If you have leftover cabbage indicator, store it in the lidded jar and place it in the refrigerator. It will keep for two weeks!
Page 2
Experiment Chart
Household Material Prediction Do you think this household material is an acid, base, or neutral?
Observations What color change do you see?
Conclusion Is the household material an acid, base, or neutral?
Baking soda
Hand soap
Lemon juice/Vinegar
Tap water
Soda (clear would be best)
Now find some other items at home to test! Enter them into the blank rows below
Color Change Chart
BASIC NEUTRAL ACIDIC
pH
SC
ALE
Página 1
¡Haz tu propio indicador de pH con la Dra. en química Sophia Tran!
Materiales necesarios:
Matraces/vasos de precipitado (alternativa: vasos de plástico pequeños, uno por cada material del hogar que se analizará)
Pipetas (alternativas: cuchara, gotero o popote; en el caso del popote, coloca el dedo en el extremo superior para retener el líquido)
Cilindro graduado con medidas de 5 ml (alternativas: vaso dosificador de jarabe para la tos o una cuchara para medir 1 cucharadita)
Una col morada (repollo morado)
Cuchillo y tabla para picar
Olla, colador, agua y estufa
Frasco con tapa (para guardar el líquido indicador de col, según sea necesario)
Materiales del hogar para analizar: bicarbonato de sodio, jabón para las manos, jugo de limón, vinagre, agua del grifo, cualquier refresco o bebida gaseosa transparente
Explicación: La escala de pH nos indica si algo es ácido, neutro o base. La escala va del 0 al 14. Si algo marca menos que 7, significa que es ácido. Si marca más que 7, es una base. Si marca 7, es neutro: ni ácido ni base. Entender el pH de una sustancia química es importante para las actividades cotidianas, como cocinar y trabajar en el jardín, las funciones de nuestro organismo, y muchas cosas más. Los ácidos generalmente son muy agrios (como el jugo de limón) y las bases suelen ser amargas (si alguna vez te entró champú en la boca por accidente, sabrás que el jabón es una base). Si combinas partes iguales de un ácido y una base, ¡Se neutralizarán entre sí! Si algo es demasiado ácido o básico, puede dañar o matar otras cosas, como las plantas.
Instrucciones de la actividad: cómo hacer un indicador de pH con una col morada (repollo morado) y analizar el pH de materiales del hogar ¡Pídele ayuda a un adulto para usar el cuchillo, la estufa y para hervir el agua!
1) Usa la tabla para picar y el cuchillo para cortar una col morada en trozos más bien grandes. Coloca los trozos en la olla, agrega agua para que la col quede sumergida, llévala a la estufa y deja que hierva 5 minutos. Usa el colador para colectar los trozos de col y recoger el líquido en el frasco. Este líquido será el “indicador de col”. Déjalo enfriar antes de usar. Mientras se enfría, completa la columna de predicciones en el cuadro del experimento de la página 2.
2) Vierte aproximadamente 5 ml del líquido indicador de col en un matraz (vaso de precipitado) o vaso de plástico. Usa la pipeta para agregar unas gotas del material del hogar que estés analizando al líquido indicador de col. Consejo: Si el material del hogar es sólido, disuélvelo en un poco de agua antes de agregarlo al líquido indicador de col.
3) Registra el cambio de color en la columna de observaciones en el cuadro del experimento. Asegúrate de escribirlo en la fila correspondiente al material que analizaste. Luego, usa el cuadro de cambio de color de la página 2 para determinar si el material que analizaste es un ácido o una base.
4) ¡Busca otros materiales para analizar que tengas en la casa que no estén en el cuadro del experimento! ¡Recuerda preguntarle a tus padres antes de analizarlos!
5) Toma uno de los ácidos y una de las bases del cuadro. Agrega partes iguales del ácido y de la base en un matraz o vaso de plástico, y analiza el pH de la mezcla resultante. ¿Lograste neutralizar las sustancias químicas?
Si te sobra líquido indicador de col, guárdalo en el frasco con tapa en el refrigerador. Se conservará hasta por dos semanas.
Página 2
Cuadro del experimento
Material del hogar Predicción ¿Crees que este material es ácido, base o neutro?
Observaciones ¿Qué cambio de color observas?
Conclusión ¿El material es ácido, base o neutro?
Bicarbonato de sodio
Jabón para las manos
Jugo de limón o vinagre
Agua del grifo
Bebida gaseosa transparente
Ahora, busca otros materiales para analizar que tengas en casa. Escríbelos en las filas en blanco a continuación.
Cuadro de cambio de color
BÁSICO NEUTRO ÁCIDO
ESC
ALA
DE
pH
