Nickel has 28 protons if it has 31 neutrons, what is it’s atomic mass?

15.3 g of nano3 were dissolved in 100g of water in a calorimeter. The temperature of the water drops from 25.00°c to 21.56°c. Ca

Arturiano [62]

Answer:

0.259 kJ/mol ≅ 0.26 kJ/mol.

Explanation:

To solve this problem, we can use the relation:

Q = m.c.ΔT,

where, Q is the amount of heat absorbed by ice (Q = ??? J).

m is the mass of the ice (m = 100.0 g).

c is the specific heat of water (c of ice = 4.186 J/g.°C).

ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = 21.56°C - 25.0°C = -3.44°C).

∵ Q = m.c.ΔT

∴ Q = (100.0 g)(4.186 J/g.°C)(-3.44°C) = -1440 J = -1.44 kJ.

∵ ΔH = Q/n

n = mass/molar mass = (100.0 g)/(18.0 g/mol) = 5.556 mol.

∴ ΔH = (-1.44 kJ)/(5.556 mol) = 0.259 kJ/mol ≅ 0.26 kJ/mol.

3 0

3 years ago

9. Using the balanced equation from Question #8, how many grams of lead will be produced if 2.54 grams of PbS is burned with 1.8

MissTica

Answer: 2.24 grams of Pb

Explanation:

Step 1

Balanced chemical reaction;

2PbS + 3O2 → 2Pb + 2SO3

Step 2

Moles of both PbS and O2

Moles = mass / molar mass

Moles of PbS = 2.54 g / 239.3 g/mol = 0.0108 moles

Moles of O2 = 1.88 / 32 g/mol = 0.0588 moles

Step 3

Finding the limiting reactant.

Limiting reactant, is that reactant which is completely used in the reaction;

If we assume that PbS is the limiting reactant;

We have 0.0588 moles of O2. This needs ( 0.0588 * 2) / 3 = 0.0392 moles of PbS to fully react. But we have only 0.0108 moles of PbS available. That means that the PbS will be completely consumed hence the limiting reactant

If we assume O2 is the limiting reactant;

We have 0.0108 moles of PbS. That needs ( 0.0108 * 3) / 2 = 0.0162 moles of O2. But we have 0.0588 moles of O2 which is in excess further confirming that PbS is the limiting reactant since it will be depleted in the reaction.

Step 4

Moles of lead

For this step we apply the mole ratios with the limiting reactant;

Mole ratio of PbS : Pb = 2 : 2 = 1 : 1

Therefore;

Moles of Pb = (0.0108 moles * 1 ) 1

Moles of Pb =0.0108 moles

Step 5

Mass of Pb

Mass = moles * molar mass

Mass of Pb =0.0108 moles * 207.2 g/mol

Mass of Pb = 2.24 grams

5 0

2 years ago

Hydrogen peroxide can decompose to water and oxygen by the following reaction

mestny [16]

To begin calculating, there is one thing you need to remember : $1 mole of H2O2=34.0148 g$
Then we have $5.00g of H2O2=5/34.0148=0.146995$
As you know decomposition of 2moles now has prodused 196kj
So, q is made due $0.146995 moles of H2O2$ $=(-196/2)*0.146995=-14.40551Kj$
I'm sure it will help.

6 0

2 years ago

How does elements and compounds reacting together is essential in everyday matters?

MrMuchimi

Chemical reactions are at the essence of just about every biological and physical process in the whole universe. Stars form due to chemical reactions, our sun flamed up also because of chemical reactions in its core. Life basically evolved on Earth as an outcome of chemical reactions. The "circle of life" is, at its quintessence, a sequence of chemical reactions. Also our capacity to move and think is an outcome of chemical reactions that happen inside our bodies. Chemical reactions are the reason why new forms of matter are created. Chemical reactions make us comprehend the properties of matter. Chemical reactions make food into fuel for our bodies, they make fireworks blow up, they change food when it is cooked, they make soap remove dirt, and a lot more. Chemical reactions contribute to solving crimes and unravel mysteries. We can even find out which planets and moons are most likely to be able to preserve life. The most significant and momentous discovery made by humans, fire, is just a chemical reaction. Nothing would ever change without chemical reactions

3 0

2 years ago

Lithium sulphate is used in some medicines and its presence in a medicine can be shown by two a combination of two tests a)expla

shtirl [24]

Answer:

A flame test could help by seeing what things it could catch on fire from or the things that could happen with acids etc. I would test the medicine by asking someone who has had it in their life, asking doctors or I would maybe use it myself maybe. (I don’t know about c, sooo sorry)

6 0

2 years ago