# Stoichiometry Flashcards Preview

## AP Chemistry > Stoichiometry > Flashcards

Flashcards in Stoichiometry Deck (40)
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## How do you calculate the mass of one mole of a substance?

### Find the atomic weight of each element in the molecular formula. Multiply that weight by the subscript (number of that atom present). Add these numbers together to get the total sum. Ex: 1 mole of H2O has a mass of 18 g. (1 * 2) + (16 * 1) = 18

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What is the weight of:

## 1 mole of carbon dioxide, CO2?

### 44 g To calculate the weight of 1 mole of a substance, add the atomic weights of every atom in the molecular formula. Remember approximation is almost always good enough on most chemistry tests, especially on the AP Chemistry Exam. Weight (CO2) = 12 + 2(16) = 44 g

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How many moles are in:

## 32 g of SO2?

### 1/2 a mole 1 mole of SO2 has a mass of: 32 + 2(16) = 64 g Thus, 32 g is one half a mole.

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## Knowing that the oxidation state of the oxygen atoms in NO3- is -2, what is the oxidation state of the nitrogen?

### The oxidation state of the nitrogen is +5 1) Add up the total oxidation for all the molecule's known atoms: (-2) * 3 = -6 2) Subtract that amount from the molecule's net charge: (-1) - (-6) = +5 The remaining amount is the unknown atom's oxidation state.

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What oxidation state is usually assigned to the following?

## Alkali metals Alkali Earth Metals Halogens

### Alkali Metals = +1 Alkali Earth Metals = +2 Halogens = -1 Elements in these groups will typically give up or accept their standard number of electrons when making bonds in compounds.

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What is the oxidation state of the oxygen atom(s) in the following?

## O2 H2O H2O2

### In O2, O = 0 The oxidation number for every element in its standard state is zero. In H2O, O = -2 This is oxygen's typical oxidation state in compounds. In H2O2, O = -1 Peroxides are the one compound where oxygen has this oxidation state.

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What is the oxidation state of the nitrogen atom in the following?

## NO NO2 HNO3

### In NO, N = +2 Oxygen's oxidation state is -2, and the molecule is neutrally charged, so the nitrogen must be +2. In NO2, N = +4 Oxygen's oxidation state is -2 (total of -4 for both), and the molecule is neutrally charged, so the nitrogen must be +4. In HNO3, N = +5 Oxygen's oxidation state is -2 (total of -6 for all 3), hydrogen's oxidation state is +1, and the molecule is neutrally charged, so the nitrogen must be +5.

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What is the oxidation state of the sulfur atom in the following?

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