Solid added to liquid and the solid floats down to bottom of container physical or chemical change?

borishaifa [10]

Question 17:

False; cutting hair would change what it looks like but, braiding it keeps it the same substance it is.

Question 18 :

My best guess would either be A or D. I would lean more towards D because if there are different mixtures then it depends on what you are mixing.

Hope it helps in some way. <3

5 0

2 years ago

As with other ionic compounds, potassium bromate, KBrO3, dissociates into ions when it dissolves in water. If 13.8 g of KBrO3 is

chubhunter [2.5K]

Answer:

ΔH of dissociation is 38,0 kJ/mol

Explanation:

The dissociation reaction of KBrO₃ is:

KBrO₃ → K⁺ + BrO₃⁻ 

This dissolution consume heat that is evidenced with the decrease in water temperature.

The heat consumed is:

q = CΔTm

Where C is specific heat of water (4,186 J/mol°C)

ΔT is the temperature changing (18,0°C - 13,0°C = 5,0°C)

And m is mass of water (150,0 mL ≈ 150,0 g)

Replacing, heat consumed is:

q = 3139,5 J ≡ 3,14 kJ

13,8 g of KBrO₃ are:

13,8 g×(1mol/167g) = 0,0826 moles

Thus, ΔH of dissociation is:

3,14kJ / 0,0826mol = 38,0 kJ/mol

I hope it helps!

3 0

2 years ago

If the chemist mistakenly makes 250 mL of solution instead of the 200 mL, what molar concentration of sodium nitrate will the ch

Evgesh-ka [11]

Answer:

0.120M is the concentration of the solution

Explanation:

Assuming the mass of sodium nitrate dissolved was 2.552g

Molar concentration is an unit of concentration widely used in chemsitry defined as the moles of solute (In this case NaNO3) in 1L of solution.

To find this question we must find the moles of NaNO3 in 2.552g. With this mass and the volume (250mL = 0.250L) we can find molar concentration as follows:

Moles NaNO3 -Molar mass: 84.99g/mol-

2.552g * (1mol / 84.99g) = 0.0300 moles NaNO3

Molar concentration:

0.0300 moles NaNO3 / 0.250L =

<h3>0.120M is the concentration of the solution</h3>

7 0

3 years ago

GenAlex Medical, a leading manufacturer of medical laboratory equipment, is designing a new automated system that can detect nor

SOVA2 [1]

Answer:

The minimum concentration of acetaminophen that can be detected by new= 10μg/mL

Volume of blood sample=2ml

Minimum mass of acetaminophen that can be detected by automated system= 10×2= 20μg= 0.020mg

6 0

2 years ago

A student was asked to prepare 500.0 mL of 6.0 M NaOH. The student measured 120.0 g of NaOH and placed it in a 1000 mL beaker. T

Morgarella [4.7K]

Answer:

The concentration of the solution will be much lower than 6M

Explanation:

To prepare a solution of a solid, the appropriate mass is taken and accurately weighed in a weighing balance and then made up to mark with distilled water.

From

n= CV

n = number of moles m/M( m= mass of solid, M= molar mass of compound)

C= concentration of substance

V= volume of solution

m=120g

M= 40gmol-1

V=500ml

120/40= C×500/1000

C= 120/40× 1000/500

C=6M

This solution will not be exactly 6M if the student follows the procedure outlined in the question. The actual concentration will be much less than 6M.

This is because, solutions are prepared in a standard volumetric flask. Using a 1000ml beaker, the student must have added more water than the required 500ml thereby making the actual concentration of the solution less than the expected 6M.

7 0

3 years ago