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3 years ago

This occurs when energy is added or removed

Chemistry

2 answers:

zmey [24]3 years ago

7 0

Answer:

melting

Explanation:

Aliun [14]3 years ago

6 0

Answer:

physical change

Explanation:

i googled it and that's what came up sry if it's wrong (change of state came up too if that doesn't work)

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Which term best defines the feeding behavior of most gulls?

White raven [17]

Answer:

Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century, most gulls were placed in the genus

6 0

2 years ago

An iron ore sample weighing 0.5562 g is dissolved HCl (aq), and the iron is obtained as Fe2 in solution. This solution is then t

erik [133]

Answer:

$\% Fe^{+2}=70%$

Explanation:

Hello,

In this case, we could considering this as a redox titration:

$Fe^{+2}+(Cr_2O_7)^{-2}\rightarrow Fe^{+3}+Cr^{+3}$

Thus, the balance turns out (by adding both hydrogen ions and water):

$Fe^{+2}\rightarrow Fe^{+3}+1e^-\\(Cr_2^{+6}O_7)^{-2}+14H^++6e^-\rightarrow 2Cr^{+3}+7H_2O\\\\6Fe^{+2}+(Cr_2^{+6}O_7)^{-2}+14H^++6e^-\rightarrow Cr^{+3}+7H_2O+6Fe^{+3}+6e^-$

Thus, by stoichiometry, the grams of Fe+2 ions result:

$m_{Fe^{+2}}=0.04021\frac{molK_2Cr_2O_7}{L}*0.02872L*\frac{6molFe^{+2}}{1molK_2Cr_2O_7}*\frac{56gFe^{+2}}{1molFe^{+2}}=0.388gFe^{+2}$

Finally, the mass percent is:

$\% Fe^{+2}=\frac{0.388g}{0.5562g}*100\%\\ \% Fe^{+2}=70%$

Best regards.

8 0

3 years ago

How many liters of water can be formed if 1.65 liters of ethylene are consumed

alexandr1967 [171]

Ethylene Burns in the presence of O₂ to produce CO₂ and H₂O vapors;

C₂H₄ + 3 O₂ → 2 CO₂ + 2 H₂O

According to equation,

22.4 L (1 mole) C₂H₄ reacts completely to produce = 44.8 L (2 moles) of H₂O

So,

1.65 L of C₂H₄ on complete reaction will produce = X L of H₂O

Solving for X,

X = (1.65 L × 44.8 L) ÷ 22.4 L

X = 3.3 L of H₂O

4 0

4 years ago

Cuando el oxígeno reacciona con el calcio produce un sólido blanco muy utilizado en la preparación de cementos. ¿Cuál de las sig

8_murik_8 [283]

Answer:

2Ca + O₂ → 2CaO

Explanation:

Cuando el Calcio (Ca) reacciona con oxígeno (O₂) se produce cal (CaO). La cal es un sólido inodoro de color blanco a grisáceo. La cal es un óxido que se encuentra presente en el cemento y su cuantificación permite determinar la calidad y el tipo de cemento a utilizar.

La reacción que describe el proceso anterior es:

Ca + O₂ → CaO

Para balancear los oxígenos, se deben poner 2 CaO como producto:

Ca + O₂ → 2CaO

Para balancear los calcios, se pone como coeficiente del Ca un 2:

Esta última es la reacción que describe el proceso anterior

6 0

3 years ago

Select the single best answer What is the purpose of an acid-base buffer? OA. To maintain both relatively constant pH and pK, in

Evgesh-ka [11]

Answer: Option (B) is the correct answer.

Explanation:

An aqueous solution that consists of a mixture of weak base and its conjugate acid or a weak acid and its conjugate base is known as a buffer.

When we add a strong acid or base into this mixture then the change in pH of this mixture is very small.

In a buffer solution, pH depends on the ratio of concentration of base divided by concentration of acid.

It is known that for a given temperature, the value of $pK_{a}$ remains constant.

Therefore, relation between pH and $pK_{a}$ will be as follows.

pH = $pK_{a} + (log \frac{base}{acid})$

Thus, we can conclude that the purpose of an acid-base buffer is to maintain a relatively constant pH in a solution.

8 0

3 years ago