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3 years ago

How do you know if a reaction is exothermic? Enter your answer in the space provided

1 answer:

monitta3 years ago

3 0

Exothermic is a chemical reaction in which heat is released. Lighting a candle is an example of an exothermic because the flame is the heat being released.

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A 1.0 g sample of hydrogen reacts completely with 19.0 g of fluorine to form a compound of hydrogen and fluorine. a. What is the

Rashid [163]

Explanation:tr

a) Molar mass of HF = 20 g/mol

Atomic mass of hydrogen = 1 g/mol

Atomic mass of fluorine = 19 g/mol

Percentage of an element in a compound:

$\frac{\text{Number of atoms of element}\times \text{Atomic mass of element}}{\text{Molar mass of compound }}\times 100$

Percentage of fluorine:

$\frac{1\times 19 g/mol}{20g/mol}\times 100=95\%$

Percentage of hydrogen:

$\frac{1\times 1g/mol}{20 g/mol}\times 100=5\%$

b) Mass of hydrogen in 50 grams of HF sample.

Moles of HF = $\frac{50 g}{20 g/mol}=2.5 mol$

1 mole of HF has 1 mole of hydrogen atom.

Then 2.5 moles of HF will have:

$1\times 2.5 mol=2.5 mol$ of hydrogen atom.

Mass of 2.5 moles of hydrogen atom:

1 g/mol × 2.5 mol = 2.5 g

2.5 grams of hydrogen would be present in a 50 g sample of this compound.

c) As we solved in part (a) that HF molecules has 5% of hydrogen by mass.

Then mass of hydrogen in 50 grams of HF compound we will have :

5% of 50 grams of HF = $\frac{5}{100}\times 50 g=2.5 g$

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3 years ago

The element whose atomic number is 13 has how many valence electrons electron configuration

RideAnS [48]

It is in Group 3A = 3 valence electrons

Electron Config. = 1s2 2s2 2p6 3s2 3p1

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3 years ago

The product of a combination reaction is Ba(OH)2 . If one of the reactants is H2O , what is the other reactant

Gnoma [55]

BaO..........................

7 0

3 years ago

Read 2 more answers

What is the difference between elements, compounds and mixtures in terms of particle theory?

zvonat [6]

Element is a single substance, while a compound is the chemical combination of two or more elements, and mixture is the physical combination of two or more elements that can easily be reversed to obtain it's previous state.

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3 years ago

For a comparative or experimental investigation, scientists often make a testable ___ about a scientific question, and then they

Morgarella [4.7K]

Answer:

B. Hypothesis

Explanation: A hypothesis is a guess of what will or might happen before an experiment.

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3 years ago