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3 years ago

What could you change or add to your models based on what you have learned about molecules and phases so far?

2 answers:

5 0

Answer:Phase changes require either the addition of heat energy (melting, evaporation, and sublimation) or subtraction of heat energy (condensation and freezing). ... Changing the amount of heat energy usually causes a temperature change.

Explanation:

babymother [125]3 years ago

3 0

Ummm I don’t know ‍♀️

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7 g of table salt is add to water in a dish. The dish is then heated until all the water evaporates. Assuming no chemical reacti

Aleks04 [339]

Answer:

7 grams

Explanation:

The water evaporates leaving the same amount of salt behind

hope this helps...

8 0

3 years ago

A 0.200 M solution of a weak acid, HA, is 9.4% ionized. Using this information, calculate Ka for HA.

slavikrds [6]

${ \qquad\qquad\huge\underline{{\sf Answer}}}$

Let's solve ~

Initial concentration of weak acid HA = 0.200 M

and dissociation constant ( ${ \alpha}$ ) is :

$\qquad \sf \dashrightarrow \: \alpha = \frac{dissociation \: \: percentage}{100}$

$\qquad \sf \dashrightarrow \: \alpha = \frac{9.4}{100} = 0.094$

Now, at initial stage :

$\textsf{ Conc of HA = 0.200 M}$

$\textsf{Conc of H+ = 0 M}$

$\textsf{Conc of A - = 0 M}$

At equilibrium :

$\textsf{Conc of HA = 0.200 - 0.094(0.200) = 0.200(1 - 0.094) = 0.200(0.906) = 0.1812 M}$

$\textsf{Conc of H+ = 0.094(0.200) = 0.0188 M}$

$\textsf{Conc of A - = 0.094(0.200) = 0.0188 M}$

Now, we know :

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{[H+] [A-]}{[HA]}}$

( big brackets represents concentration )

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{0.0188×0.0188}{0.1812}}$

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{0.00035344}{0.1812}}$

$\qquad \sf \dashrightarrow \: { K_a \approx 0.00195 }$

$\qquad \sf \dashrightarrow \: {K_a \approx 1.9 × {10}^{-3} }$

7 0

2 years ago

Why an aspirin tablet works faster if it is crushed rather than swallowed whole?

givi [52]

Answer: because the tablet is already crushed and is easy for the organism to absorb instead of having to break it down

Explanation:

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3 years ago

Looking across period 4 of the periodic table, potassium (atomic number 19) is followed by calcium (atomic number 20), which is

Anika [276]

Atomic radius increases as you move left across the periodic table, therefore, potassium will have the largest atomic radius

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3 years ago

How many electrons are located in the outermost energy level in the Bohr model of a boron atom? hint it not 4

borishaifa [10]

2 is the answer iam not sure about it
Yes

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3 years ago