Mixing Lemon Juice and Milk - ES - PS - Structure and Properties

Last updated 5 months ago

6 Nsɛmmisa

Hyɛ no nsow a efi ɔkyerɛwfo no hɔ:

Directions: Use the information provided and your knowledge of Physical Science to answer the following questions. Show all work where necessary.

Akwankyerɛ

Directions: Use the information provided and your knowledge of Physical Science to answer the following questions. Show all work where necessary.

Mixing Lemon Juice and Milk

Diagram 1.

Close-up of milk with many bubbles and droplets on its surface Source:

https://saraichinwag.com/what-happens-when-you-mix-lemon-juice-and-milk

Phenomenon

Students add a spoonful of lemon juice to warm milk. Within moments, the milk begins to curdle, forming soft clumps called curds while leaving a watery liquid called whey. The texture, smell, and appearance all change.

Students ask:

Did we just make a mixture, or did we form a new substance?

This investigation helps them collect evidence that mixing can sometimes create new substances with different properties.

Some mixtures simply blend ingredients together without changing them, like sand mixed with salt. But other mixtures cause substances to change into new materials. When warm milk is mixed with lemon juice, the acid in the lemon juice interacts with the proteins in the milk. These proteins change shape and form new solid clumps called curds. This process is called coagulation.

Before the lemon juice is added, the milk is a smooth, white liquid. It has a mild smell and pours easily. After lemon juice is mixed in, the milk separates into lumpy curds and a watery liquid. The smell becomes slightly sour, and the texture becomes thick and chunky. These new properties show that the original milk is no longer present in the same form.

Because the substances after mixing have different properties than the substances before, this is a sign that new substances have formed. Students can observe these changes and collect evidence that this is more than just a mixture - it is a chemical change.

Table 1.

Property Observed	Before Mixing	After Mixing
Appearance	Smooth white liquid	Curds + watery whey
Smell	Mild	Slightly sour
Texture	Thin, pourable	Thick, lumpy
New Solid Formed?	No	Yes

Graph of Information - Figure 1.

Bar graph titled 'Formation of New Solid When Milk is Mixed with Lemon Juice' showing no new solid before mixing and a new solid after mixing.

Table 2.

Time (minutes)	Mass of Curds (g)
0	0
2	12
4	18
6	22

Graph of Information - Figure 2.

Graph titled 'Formation of Curds Over Time' showing mass of curds increasing from 0 g at 0 minutes to 22 g at 6 minutes.

Ɛhia

Look at Table 1. What changes do you observe in appearance, smell, and texture after the lemon juice is mixed with the milk?

DOK 3

5-PS1-4

Ɛhia

Using Figure 1, describe what happens to the formation of a solid before mixing compared to after mixing.

DOK 3

5-PS1-4

Ɛhia

Which observation best supports the idea that new substances formed?

The milk was white before mixing

The mixture smelled slightly sour

A new solid formed that was not present before

The milk was warmed before mixing

DOK 2

5-PS1-4

Ɛhia

How does mixing warm milk and lemon juice provide evidence that new substances can form when materials are mixed?
Respond using Claim, Evidence, and Reasoning.

DOK 4

5-PS1-4

Ɛhia

Look at Table 2 and Figure 2. How does the mass of curds change over time, and what does this show about what is happening in the mixture?

DOK 3

5-PS1-4

Ɛhia

Which piece of evidence is most important for distinguishing this investigation from a simple mixture?

The milk changes temperature

The smell becomes slightly sour

The mass of curds increases over time

The milk and lemon juice are liquids

DOK 2

5-PS1-4

Mixing Lemon Juice and Milk - ES - PS - Structure and Properties

Mixing Lemon Juice and Milk - ES - PS - Structure and Properties

Mixing Lemon Juice and Milk

Diagram 1.

Phenomenon

Table 1.

Graph of Information - Figure 1.

Table 2.

Graph of Information - Figure 2.

Look at Table 1. What changes do you observe in appearance, smell, and texture after the lemon juice is mixed with the milk?

Using Figure 1, describe what happens to the formation of a solid before mixing compared to after mixing.

Which observation best supports the idea that new substances formed?

How does mixing warm milk and lemon juice provide evidence that new substances can form when materials are mixed?Respond using Claim, Evidence, and Reasoning.

Look at Table 2 and Figure 2. How does the mass of curds change over time, and what does this show about what is happening in the mixture?

Which piece of evidence is most important for distinguishing this investigation from a simple mixture?

Mixing Lemon Juice and Milk

Diagram 1.

Phenomenon

Table 1.

Graph of Information - Figure 1.

Table 2.

Graph of Information - Figure 2.

Look at Table 1. What changes do you observe in appearance, smell, and texture after the lemon juice is mixed with the milk?

Using Figure 1, describe what happens to the formation of a solid before mixing compared to after mixing.

Which observation best supports the idea that new substances formed?

How does mixing warm milk and lemon juice provide evidence that new substances can form when materials are mixed?Respond using Claim, Evidence, and Reasoning.

Look at Table 2 and Figure 2. How does the mass of curds change over time, and what does this show about what is happening in the mixture?

Which piece of evidence is most important for distinguishing this investigation from a simple mixture?

How does mixing warm milk and lemon juice provide evidence that new substances can form when materials are mixed?
Respond using Claim, Evidence, and Reasoning.

How does mixing warm milk and lemon juice provide evidence that new substances can form when materials are mixed?
Respond using Claim, Evidence, and Reasoning.