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3 years ago

Methods scientist use to determine a change in physical or chemical change in an Item

1 answer:

8 0

They'd observe any new substances or new color, and temp. that is irreversible.

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Mammals and plants do not belong in the same domain. <br><br> Fact: <br><br> Evidence:

Zepler [3.9K]

False

Fact: Mammals and plants belong to the same domain, the Eukarya domain.

Evidence :All the organisms that possess a eukaryotic cell, plants, animals, protists, and fungi are in the Eukarya domain.

3 0

3 years ago

Which chemical formula represents both an element and a molecule?

victus00 [196]

Answer:

Explanation:

element - a basic substance that can't be simplified (hydrogen, oxygen, gold, etc...) molecule - two or more atoms that are chemically joined together (H2, O2, H2O, C6H12O6, etc...) compound - a substance that contains more than one element (H2O, C6H12O6, etc...)

5 0

2 years ago

HC2H3O2 (aq) + H2O (l) ⇔ C2H3O2- (aq) + H3O+ (aq) Ka = 1.8 x 10-5

marin [14]

The concentration of [H3O⁺]=2.86 x 10⁻⁶ M

<h3>Further explanation</h3>

In general, the weak acid ionization reaction

HA (aq) ---> H⁺ (aq) + A⁻ (aq)

Ka's value

$\large {\boxed {\bold {Ka \: = \: \frac {[H ^ +] [A ^ -]} {[HA]}}}}$

Reaction

HC₂H₃O₂ (aq) + H₂O (l) ⇔ (aq) + H₃O⁺ (aq) Ka = 1.8 x 10⁻⁵

$\tt Ka=\dfrac{[C_2H_3O^{2-}[H_3O^+]]}{[HC_2H_3O_2]}}\\\\1.8\times 10^{-5}=\dfrac{0.22\times [H_3O^+]}{0.035}$

[H₃O⁺]=2.86 x 10⁻⁶ M

5 0

3 years ago

You need to produce a buffer solution that has a pH of 5.31. You already have a solution that contains 10. mmol (millimoles) of

Karolina [17]

Answer:

37 mmol of acetate need to add to this solution.

Explanation:

Acetic acid is an weak acid. According to Henderson-Hasselbalch equation for a buffer consist of weak acid (acetic acid) and its conjugate base (acetate)-

$pH=pK_{a}(acetic acid)+log[\frac{mmol of CH_{3}COO^{-}}{mmol of CH_{3}COOH }]$

Here pH is 5.31, $pK_{a}$ (acetic acid) is 4.74 and number of mmol of acetic acid is 10 mmol.

Plug in all the values in the above equation:

$5.31=4.74+log[\frac{mmol of CH_{3}COO^{-}}{10}]$

or, mmol of $CH_{3}COO^{-}$ = 37

So 37 mmol of acetate need to add to this solution.

3 0

3 years ago

How many Noble gases are there?

melomori [17]

Answer:

six noble gases

Here are five of the six noble gases: helium, neon, argon, kypton and xeon. They're all colourless and transparent. Krypton and xeon form compounds only with difficulty. Helium, neon and argon don't form compounds at all.

3 0

3 years ago

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