When a machine does work, a trade-off occurs. Which of the following best exemplifies this trade-off?

Under which conditions will sugar most likely dissolve fastest in a cup of water?

zheka24 [161]

If the cup of water contained hot water. Sugar will dissolve a lot slower if it was in room temperature and even slower if it was in cold water.

3 0

3 years ago

What is the reason carbon atoms are the most versatile building blocks of the molecules used by living organisms?

WITCHER [35]

Explanation:

Atomic number of carbon is 6. So, 4 valence electrons are present.

Therefore, it can form 4 covalent bonds with varying bond angles by sharing its valence electrons.

Catenation is also an important property of carbon. Catenation is bonding with atoms of same element. Carbon skeleton can be formed in any direction and can vary in length, branching, and ring structure.

Elements required for making most of the molecules in living organisms are:

C, H, N, O, P and S

Carbon easily form covalents with other 5 elements.

These properties make carbon most versatile building blocks of the molecules used by living organisms.

4 0

3 years ago

If acetic acid is the only acid that vinegar contains (ka=1.8×10−5), calculate the concentration of acetic acid in the vinegar.

kicyunya [14]

Ethanoic (Acetic) acid is a weak acid and do not dissociate fully. Therefore its equilibrium state has to be considered here.

$CH_{3}COOH \ \textless \ ---\ \textgreater \ H^{+} + CH_{3}COO^{-}$

In this case pH value of the solution is necessary to calculate the concentration but it's not given here so pH = 2.88 (looked it up)

pH = 2.88 ==> $[H^{+}]$ = $10^{-2.88}$ = 0.001 $moldm^{-3}$

The change in Concentration Δ $[CH_{3}COOH]$ = 0.001 $moldm^{-3}$

  CH3COOH H+ CH3COOH
Initial   $moldm^{-3}$      $x$ 0 0

Change $moldm^{-3}$ -0.001 +0.001 +0.001

Equilibrium $moldm^{-3}$ $x$ - 0.001 0.001 0.001


Since the $k_{a}$ value is so small, the assumption
$[CH_{3}COOH]_{initial} = [CH_{3}COOH]_{equilibrium}$ can be made.

$k_{a} = [tex]= 1.8*10^{-5} = \frac{[H^{+}][CH_{3}COO^{-}]}{[CH_{3}COOH]} = \frac{0.001^{2}}{x}$

Solve for x to get the required concentration.

note: 1.)Since you need the answer in 2SF don&t round up values in the middle of the calculation like I've done here.

2.) The ICE (Initial, Change, Equilibrium) table may come in handy if you are new to problems of this kind

Hope this helps!

8 0

4 years ago

Describe what conditions exist in water molecules to make them dipolar.

lesantik [10]

<span>The bent geometry of the water molecule gives a slight overall negative charge to the oxygen side of the molecule and a slight overall positive charge to the hydrogen side of the molecule. This slight separation of charges gives the entire molecule an electrical polarity, so water molecules are dipolar.</span>

4 0

3 years ago

For the reaction ag2s(s) ⇌ 2 ag+ (aq) + s2- (aq), keq = 2.4 × 10-4 and the equilibrium concentration of silver ion is [ag+] = 2.

Juliette [100K]

Answer : The concentration of silver ion is, $3.8\times 10^{-3}M$

Explanation :

Equilibrium constant : It is defined as the equilibrium constant. It is defined as the ratio of concentration of products to the concentration of reactants.

The equilibrium expression for the reaction is determined by multiplying the concentrations of products and divided by the concentrations of the reactants and each concentration is raised to the power that is equal to the coefficient in the balanced reaction.

As we know that the concentrations of pure solids and liquids are constant that is they do not change. Thus, they are not included in the equilibrium expression.

The given equilibrium reaction is,

$Ag_2S(s)\rightleftharpoons 2Ag^+(aq)+S^{2-}(aq)$