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3 years ago

How can you use evidence to determine if a change is physical or chemical?

2 answers:

7 0

A physical change has Color, Shape, and anything that is physically changed. A chemical change is when you can’t really tell for example when a formation of new atoms. Even creating 1 or more new substances.

irakobra [83]3 years ago

4 0

Physical change is the color, shape stuff like that and chemical change is once it’s changed it can’t go back

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What are the two flasks for measuring the liquid volume?

aleksandrvk [35]

Answer:

Liquid volume is usually measured using either a graduated cylinder or a buret.

7 0

3 years ago

Determine the acid dissociation constant for a 0.020 m formic acid solution that has a ph of 2.74. formic acid is a weak monopro

Setler [38]

Answer:

Ka = 1.82x10⁻⁴

Explanation:

To solve this problem, we need a basis. In this case, we need the overall reaction and a ICE chart. So, let's write the overall reaction first:

HCOOH + H₂O <--------> H₃O⁺ + HCOO⁻ Ka = ?

Now that we have the overall reaction, we need to write the ICE chart. In this way we can determine what data do we have, and what do we have left to determine:

HCOOH + H₂O <--------> H₃O⁺ + HCOO⁻ Ka = ?

i) 0.02 0 0

e) 0.02-x x x

The Ka expression is:

Ka = [H₃O⁺] [HCOO⁻] / [HCOOH]

Replacing the given data we have:

Ka = x² / 0.02 - x

Now, the value of x can be calculated because we already have the pH of the formic acid, and with it, we can calculate the [H₃O⁺] with the following expression:

[H₃O⁺] = 10^(-pH)

Replacing we have:

[H₃O⁺] = 10^(-2.74) = 1.82x10⁻³ M

This is the value of x, so replacing in the Ka expression, we can calculate then, the value of Ka:

Ka = (1.82x10⁻³)² / (0.02 - 1.82x10⁻³)

7 0

3 years ago

I am using all my points to ask this. please help

ELEN [110]

Answer:

C5H7N

C10H14N2

Explanation:

ok so lets lay out this nicely

elements C H N

percentage 74 8.7 17.3

mass number 12 1 14

divided percentage by mass 6.167 8.7 1.2357

now divide the smallest number with the 4.99 7.04 1

rest for instance 1,237 is the smallest.

so 6.167÷1,237

and 8.7 ÷1.237

and 1,237 divide 1.237

now the ratio is C5H7N

now for molecular formula find Mr of C5H7N which is (12×5)+7+14=81

next divide 162.1÷81=2

so now for molecular formula just multipily everythng by 2

C10H14N2

5 0

3 years ago

write a skeletal equation for the following reaction: An aqueous solution of barium nitrate and an aqueous solution of sodium su

belka [17]

Answer: skeletal equation : $Ba(NO_3)_2(aq)+Na_2SO_4(aq)\rightarrow NaNO_3(aq)+BaSO_4(s)$

The products are sodium nitrate and barium sulphate.

balanced equation : $Ba(NO_3)_2(aq)+Na_2SO_4(aq)\rightarrow 2NaNO_3(aq)+BaSO_4(s)$

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.

The skeletal equation is:

$Ba(NO_3)_2(aq)+Na_2SO_4(aq)\rightarrow NaNO_3(aq)+BaSO_4(s)$

The balanced chemical equation is:

$Ba(NO_3)_2(aq)+Na_2SO_4(aq)\rightarrow 2NaNO_3(aq)+BaSO_4(s)$

7 0

3 years ago

Methane and water have different chemical properties because

jasenka [17]

Answer:

Explanation:

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3 0

4 years ago

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