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GrogVix [38]
3 years ago
12

A metallurgist has a 42.0-gram sample of an object of unknown composition. On testing it, the metallurgist finds that it takes 2

,878 joules of heat to melt it completely. What is the object's heat of fusion?
Chemistry
2 answers:
emmasim [6.3K]3 years ago
7 0

Answer: The object's heat of fusion is 68.52 Joules/gram.

Explanation:

Mass of the sample = 42 grams

Energy required to melt the sample completely = 2878 Joules

Q=m\times\Delta H_{fusion}

2878 Joules=42\times \Delta H_{fusion}

\Delta H_{fusion}=\frac{2878 Joules}{42 g}=68.52 Joules/gram

The object's heat of fusion is 68.52 Joules/gram.

Llana [10]3 years ago
5 0

Answer:

68.5 in sig figs 68.52 not in sig figs

Explanation:

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Answer: Molecular mass of the phenol is 94g/mol.

Explanation:

Phenol is an active ingredient in some oral anesthetics used in sore throat sprays.It is used as anesthetics to cure minor sour throat pain , minor mouth irritations etc.

For Example : Cramex , Chloraseptic sprays contains phenol as an active ingredient.

Phenol has a molecular formula of C_6H_5OH

Molecular mass of the phenol = 6(mass of carbon)+5(mass of hydrogen)+1(mass of oxygen)+1(mass of hydrogen) = 6(12)+5(1)+1(16)+(1) = 94 g/mol

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After the death of living material, the ratio of carbon-12 to carbon-14 isotopes in the material;
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How many moles are in 43.5 g of sodium hydroxide (NaOH)?
Makovka662 [10]

Answer:

1.09 moles of NaOH

Explanation:

First of all, to calculate moles, you need to find the molar mass of NaOH.

Let us first find the molar mass of NaOH then.

Na = 23.0 amu

O = 16.0

H = 1.0

They are 1 nitrogen atom, 1 oxygen atom, and one hydrogen atom.

So do this.

23.0(1) + 16.0(1) + 1.0(1) = 40 g/mol.

Now use dimensional analysis to show your work

43.5 g of NaOH * 1 mol of NaOH / 40 g/mol of NaOH

The grams cancel out.

43.5 / 40.0 = 1.0875

Use sig figs and round the answer to the nearest hundredths place.

1.0875 = 1.09

So the final answer is 1.09 moles of NaOH

Hope it helped!

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