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sveticcg [70]
3 years ago
6

Hydrochloric acid and sodium hydroxide are mixed together to form salt and water. During the reaction, the temperature of the so

lution increases. Which of these best explains why this is considered to be a chemical change?
A.No energy was destroyed.
B.Heat was iven off.
C.It involves liquid.
D.New substances formed.
Chemistry
1 answer:
sammy [17]3 years ago
6 0
The best answer among the choices is option D. New substances are being formed will best explain that this process is a chemical change. Although, it cannot be seen directly we knew that an acid and base will undergo neutralization reaction forming a salt and water. The heat given off by the reaction can be a parameter however it does not only happens for reactions. It can also happen when dissolving substances.
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How many grams of neutral salt will be obtained in the reaction of calcium oxide with 200 cm 3 of phosphoric acid solution whose
katen-ka-za [31]

Answer:

9.3 g of Ca3(PO4)2

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

3CaO + 2H3PO4 —> Ca3(PO4)2 + 3H2O

Next, we shall determine the number of mole of H3PO4 present in 200 cm³ of 0.3 mol/dm³ phosphoric acid (H3PO4) solution. This can be obtained as follow:

Molarity of H3PO4 = 0.3 mol/dm³

Volume = 200 cm³ = 200 cm³/1000 = 0.2 dm³

Mole of H3PO4 =?

Molarity = mole /Volume

0.3 = mole of H3PO4 /0.2

Cross multiply

Mole of H3PO4 = 0.3 × 0.2

Mole of H3PO4 = 0.06 mole

Next, we shall determine the number of mole of the salt, Ca3(PO4)2, obtained from the reaction. This can be obtained as shown below:

3CaO + 2H3PO4 —> Ca3(PO4)2 + 3H2O

From the balanced equation above,

2 moles of H3PO4 reacted to produced 1 mole of Ca3(PO4)2.

Therefore, 0.06 moles of H3PO4 will react to produce = (0.06 × 1)/2 = 0.03 mole of Ca3(PO4)2.

Thus, 0.03 mole of Ca3(PO4)2 is produced from the reaction.

Finally, we shall determine the mass of Ca3(PO4)2 produced as follow:

Mole of Ca3(PO4)2 = 0.03 mole

Molar mass of Ca3(PO4)2 = (40×3) + 2[31 + (16×4)]

= 120 + 2[31 + 64]

= 120 + 2[95]

= 120 + 190

= 310 g/mol

Mass of Ca3(PO4)2 =?

Mole = mass /Molar mass

0.03 = mass of Ca3(PO4)2 / 310

Cross multiply

Mass of Ca3(PO4)2 = 0.03 × 310

Mass of Ca3(PO4)2 = 9.3 g

Thus, 9.3 g of Ca3(PO4)2 was obtained from the reaction.

6 0
2 years ago
Please answer 11 and 12, I'm not sure of my answers and I'm gonna be tested on this tomorrow. Thanks!
Novay_Z [31]
11. I would say physical because the color of the item is changed and the texture and density is changed aswell.
8 0
3 years ago
calculate q for the following: 125.0 ml of 0.0500 m pb(no3)2 is mixed with 75.0 ml of 0.0200 m nacl at 25oc chegg
alexandr402 [8]

The value of Q for 125.0 ml of 0.0500 m Pb(NO3)2 is mixed with 75.0 ml of 0.0200 m NaCl at 25°C is 2.11 × 10^(-6).

Aa we know that, 125mL of 0.06M Pb(NO3)2 is mixed with 75.0 ml of 0.0200 m NaCl.

Given, T = 25°C.

<h3>Chemical equation:</h3>

Pb(NO3)2 + NaCl ---- NaNO3 + PbCl2

PbCl2 in aqueous solution split into following ions

PbCl2 ------ Pb(+2) + 2Cl-

Q = [Pb(+2)] [Cl-]^2

The Concentration of Pb(+2) ions and Cl- ions can be calculated as

[Pb(+2)] = 0.06 × 125/200

= 0.0375

[Cl-] = 0.02 × 75/200

= 0.0075

By substituting all the values, we get

[0.0375] [0.0075]^2

= 2.11 × 10^(-6).

Thus, we calculated that the value of Q for 125.0 ml of 0.0500 m Pb(NO3)2 is mixed with 75.0 ml of 0.0200 m NaCl at 25°C is 2.11 × 10^(-6).

learn more about Ions:

brainly.com/question/13692734

#SPJ4

6 0
1 year ago
1.Explain why the reactivity of group 7 decreases as you move down the group. Try to use the sentence starters here: When group
Kruka [31]

Answer: The reactivity of group 7 decreases as we move down the group because:

Explanation:

The elements of group 7 that is fluorine to iodine. The halogens are non metals and they react with metals to gain electrons. The metals loose electrons and the non metal gains it.

As we move down the group  the atomic radius gets bigger( more electron and more proton) and as a result the outer shells move further away from the nucleus.

There is more distance between the negatively charged electrons and positively charged nucleus.

Therefore the force of attraction between the shells and nucleus is lesser or weaker.

This makes attracting an extra electron from metals very difficult which results in weaker reaction.

Consequently, the reactivity decreases as we move down the group 7

5 0
3 years ago
WILL GIVE BRAINLIEST AND 5 STARS what is the purpose/ use of a Bunsen Burner
Roman55 [17]

A Bunsen burner, named after Robert Bunsen, is a common piece of laboratory equipment that produces a single open gas flame, which is used for heating, sterilization, and combustion. The gas can be natural gas (which is mainly methane) or a liquefied petroleum gas, such as propane, butane, or a mixture of both. Have A Great Day :)

5 0
3 years ago
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