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2 years ago

What is the amount of heat released when 25g of water cools 12.5 degrees C ?

1 answer:

4 0

Water can't cool at a single temperature. It must start at a higher temperature, and drop to a lower temperature in order to cool. Unless we know the other temperature, there is no way to calculate the amount of thermal energy released.

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A chemist performs the same tests on two homogeneous white crystalline solids, A and B. The results are shown in the table below

Nookie1986 [14]

Solid A contains only Covalent bonds and solid B only contains Ionic bonds. I know this because the appearance, solubility, and conductivity of solid A describes Covalent bonds.

Explanation:

Try this, but idk if it will be marked as correct.

7 0

2 years ago

SnO2 is reduced by carbon according to this reaction: SnO2 + C ???? Sn + CO2. How many liters of CO2 are produced if 300.0 grams

andrew-mc [135]

Explanation:

The given reaction is as follows.

$SnO_{2} + C \rightarrow Sn + O_{2}$

a). Molar mass of $SnO_{2}$ is [(mass of Sn) + (2 × mass of O)].

Therefore, molar mass of $SnO_{2}$ = (118.7 + 2 × 16) g/mol = 150.7 g/mol

Since, it is known that number of moles equal mass divided by molar mass. So, moles of Sn will be calculated as follows.

No. of moles = $\frac{mass}{molar mass of SnO_{2}}$

= $\frac{300 g}{150.7 g/mol}$

= 2.53 mol

As it is given that 1 mole of $SnO_{2}$ produces 1 moles of Sn and 1 moles of $CO_{2}$ . Hence, 2.53 moles of $SnO_{2}$ will also produce 2.53 moles of Sn and 2.53 moles of $CO_{2}$ .

Volume of 1 mole of $CO_{2}$ at STP is 22.4 L. Therefore, volume of 2.53 moles of $CO_{2}$ will be calculated as follows.

2.53 × 22.5 L = 56.67 L

Hence, 56.67 L of $CO_{2}$ are produced if 300.0 grams of tin are produced at STP.

b). Mass of tin is given as 1800.0 g. So, number of moles will be calculated as follows.

No. of moles = $\frac{mass}{molar mass of tin}$

= $\frac{1800.0 g}{118.7 g/mol}$

= 15.2 moles

As 15.2 moles of $SnO_{2}$ produces 15.2 moles of Sn. Therefore, weight of $SnO_{2}$ will be calculated as follows.

Mass = no. of moles × molar mass of $SnO_{2}$

= 15.2 moles × 150.7 g/mol

= 2290.64 g

Hence, 2290.64 grams of $SnO_{2}$ are required to produce 1800.0 grams of tin.

c). Mass of carbon given is 100.0 grams.

No. of moles = $\frac{mass}{molar mass of carbon}$

= $\frac{100 g}{12 g/mol}$

= 8.33 moles

As, 1 mole of carbon is produced by 1 mole of tin. So, 8.33 mole of carbon will be produced by 8.33 moles of tin.

Therefore, calculate mass of tin produced as follows.

Mass = no. of moles × molar mass of Sn

= 8.33 moles × 118.7 g/mol

= 988.8 g

Hence, 988.8 grams of tin will be produced per 100 grams of carbon used.

8 0

2 years ago

How many moles are in 123.0 grams of KClO4?

aivan3 [116]

Mole = mass / molar mass

123/138.6 = 0.8874

Mr=
K - 39.1
Cl- 35.5
O4 - (16x4= 64).

39.1+35.5+64 = 138.6

6 0

2 years ago

Read 2 more answers

A mixture of KCl and KNO3

Tems11 [23]

Answer is: <span>The percent of KCl in the mixture is closest to </span><span>a) 40%.
</span>
If we use 100 grams of mixture:
ω(K) = 44.20% ÷ 100% = 0.442.
m(K) = 0.442 · 100 g = 44.2 g.
n(K) = 44.2 g ÷ 39.1 g/mol.
n(K) = 1.13 mol.
n(KCl) + n(KNO₃) = n(K)
m(KCl) = x.
m(KNO₃) = y.
Two equtions:
1) x + y = 100 g.
2) m(KCl)/M(KCl) + m(KNO₃)/M(KNO₃) = 1.13 mol.
x/74.55 g/mol + y/101.1 g/mol = 1.13 mol.
From first equation find x = 100 - y and put in second equation:
(100 - y)/74.55 + y/101.1 = 1.13 /×101.1.
135.61 - 1.356y + y = 114.24.
0.356y = 22.37 g.
y = 62.83 g.
x = m(KCl) = 100 g - 62.83 g = 37.17 g.

8 0

2 years ago

Read 2 more answers

A state property X has a value 89.6 units. It undergoes the following changes, first increase by

yanalaym [24]

Answer:

B) -4.1 units

Explanation:

According to this question, a state property X has a value 89.6 units. It undergoes the certain changes as follows:

- first increase by 3.6 units

- then increase by another 18.7 units

- then decrease by 12.2 units

- and finally attains a value of 85.5 units

This can be mathematically represented by 89.6 - {3.6 + 18.7 - 12.2 - x) = 85.5

To get x, we say;

89.6 + 3.6 = 93.2

93.2 + 18.7 = 111.9

111.9 - 12.2 = 99.7

99.7 - 85.5 = 14.2units.

The changes that occured is represented as follows:

= (3.6 + 18.7) - (12.2 + 14.2)

= 22.3 - 26.4

= -4.1 units

7 0

2 years ago