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Illusion [34]
2 years ago
15

Classify the following changes as physical or chemical changes. a. Water boils. b. Salt dissolves in water c. Milk turns sour d.

A metal rusts.
Chemistry
1 answer:
geniusboy [140]2 years ago
6 0

Answer:

Water boils - physical change

Salt dissolves in water- chemical change

Milk turns sour- chemical change

metal rusts - chemical change

Explanation:

A chemical change refers to changes that are irreversible and the process involves the evolution of heat along with the formation of a new substance, examples include;Salt dissolves in water, Milk turns sour, metal rusts etc

The boiling of water is a physical change. The water can be cooled and the vapour condensed,hence, the boiling of water is a physical change.

Physical changes are easily reversible and no new substance is formed.

You might be interested in
Calculate the ph of a solution with a [H3O+]=5.6x10-9M
Kisachek [45]

Answer:

               pH  =  8.25

Explanation:

                   The acidity or basicity of a solution is measured by its pH. The pH scale ranges from 0 to 14. Solutions having pH from 0-6.9 are considered acidic, at 7 neutral and basic when ranging from 7.1-14.

pH is calculated as,

                                 pH  =  - log [H⁺]   ---- (1)

Where;

            [H⁺]  =  concentration of Acid

Also, for bases pH i calculated using following formula,

                                 pH  =  14 - pOH

Therefore, Putting value of H⁺ in equation 1,

                                 pH  =  - log [5.6 × 10⁻⁹]

                                pH =  8.25

The solution provided is basic in nature.

6 0
3 years ago
What is the molarity of a solution containing 8.9 g of NaOH in 550. mL of NaOH solution?
bulgar [2K]

Answer:

0.4 M

Explanation:

Molarity is defined as moles of solute, which in your case is sodium hydroxide,  

NaOH

, divided by liters of solution.

molarity

=

moles of solute

liters of solution

Notice that the problem provides you with the volume of the solution, but that the volume is expressed in milliliters,  

mL

.

Moreover, you don't have the number of moles of sodium hydroxide, you just have the mass in grams. So, your strategy here will be to

determine how many moles of sodium hydroxide you have in that many grams

convert the volume of the solution from milliliters to liters

So, to get the number of moles of solute, use sodium hydroxide's molar mass, which tells you what the mass of one mole of sodium hydroxide is.

7

g

⋅

1 mole NaOH

40.0

g

=

0.175 moles NaOH

The volume of the solution in liters will be

500

mL

⋅

1 L

1000

mL

=

0.5 L

Therefore, the molarity of the solution will be

c

=

n

V

c

=

0.175 moles

0.5 L

=

0.35 M

Rounded to one sig fig, the answer will be

c

=

0.4 M

Explanation:

6 0
2 years ago
Putting rock salt on the roads during a snowstorm is an example of: A. Boiling point elevation B. Vapor pressure raising C. Vapo
kvv77 [185]

Answer:

The correct answer is - D. Freezing point depression.

Explanation:

When rock salt is spread over snow-covered icy roads, it generates a liquid layer over it by melting from the surface thereby lowering or depression in the freezing point below the ice.

Therefore, due to this liquid layer comes into the contact with the ice present on the road and causes other ice to melts. This keeps on decreasing the volume of the ice on the road therefore, rock salts spread on the roads during a snowstorm.

7 0
3 years ago
Lactose takes years to break down on its own. But if exposed to the protein lactase, the reaction proceeds very quickly, while l
sp2606 [1]

Answer:

Enzyme  

Explanation:

An enzyme is an organic catalyst that speeds up a reaction but can be recovered unchanged.

Human lactase consists of 4092 amino acid groups and has a molar mass of about 280 000 u, so it has a complex structure.

6 0
3 years ago
Advantages and disadvantages of using tidal energy instead of non-renewable energy sources.​
Phantasy [73]

Advantages of using tidal energy:

-Environment-friendly

-A highly predictable energy source

-High energy density

-Operational and maintenance costs are low

-An inexhaustible source of energy

Disadvantages of using tidal energy:

-High tidal power plant construction costs.

-Negative influence on marine life forms.

-Location limits.

-The variable intensity of sea waves.

3 0
3 years ago
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