Questions and Answers
What does a chemical formula indicate?
Number of atoms or ions of each element that are combined in the compound
What is the formula for zinc fluoride?
ZnF2
What is the formula for the compound formed by calcium ions and chloride ions?
CaCl2
What is the formula for aluminum sulfate?
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What is the name of the compound KCLO3?
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What is the name of the compound CF4?
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What is the name of the compound N2O3?
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What is the formula for silicon dioxide?
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What is the formula for diphosphorus pentoxide?
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What is the formula for hydrochloric acid?
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What is the oxidation number of oxygen in most compounds?
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What is the oxidation number of a pure element?
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In a compound, the algebraic sum of the oxidation numbers of all atoms is equal to what?
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What is the oxidation number of oxygen in CO2?
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The molar mass of an element is the mass of one what?
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What is the formula mass of ethyl alcohol, C2H5OH?
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What is the mass of 0.240 mol of glucose, C6H12O6?
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What is the percentage composition of CO?
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The empirical formula for a compound shows what?
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What is the empirical formula for a compound that is 36.1% Ca and 63.9% Cl?
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Of the following molecular formulas for hydrocarbons, which is an empirical formula?
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A compound's empirical formula is N2O5. If the formula mass is 108 amu, what is the molecular formula?
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Study Notes
Chemical Formulas
- A chemical formula represents the elements in a compound using symbols and subscripts to indicate the number of atoms or ions per element.
- For example, the formula for zinc fluoride is ZnF2, indicating one zinc atom and two fluoride atoms.
Common Compound Formulas
- The formula for the compound formed from calcium ions and chloride ions is CaCl2, consisting of one calcium ion and two chloride ions.
- Aluminum sulfate is denoted by the formula Al2(SO4)3, which includes two aluminum atoms and three sulfate ions.
Naming Compounds
- The compound KCLO3 is known as potassium chlorate.
- CF4 is referred to as carbon tetrafluoride, denoting one carbon and four fluorine atoms.
- N2O3 is named dinitrogen trioxide, which consists of two nitrogen atoms and three oxygen atoms.
Important Chemical Formulas
- Silicon dioxide has the formula SiO2, representing one silicon atom and two oxygen atoms.
- Diphosphorus pentoxide is represented by the formula P2O5, indicating two phosphorus atoms and five oxygen atoms.
- Hydrochloric acid is denoted by HCl, consisting of one hydrogen atom and one chlorine atom.
Oxidation Numbers
- The oxidation number of oxygen in most compounds is -2, indicating a common charge.
- A pure element has an oxidation number of 0, reflecting its neutral state.
- The overall oxidation numbers of all atoms in a compound sum to the charge of the ion.
Specific Oxidation States
- In carbon dioxide (CO2), the oxidation number of oxygen is -2; hence, for two oxygen atoms, the total contribution is -4 for the carbon's oxidation state.
Molar Mass & Calculations
- The molar mass of an element is the weight of one mole, crucial for stoichiometric calculations.
- Ethyl alcohol (C2H5OH) has a molar mass of 46.07 g/mol, calculated based on its constituent atoms.
- For a sample of 10.00 mol of C2, the mass equates to 76.15 g/mol times 10.00 mol.
Percentage Composition
- For carbon monoxide (CO), the percentage composition is 43% carbon and 57% oxygen, reflecting its molecular structure.
Empirical and Molecular Formulas
- The empirical formula provides the smallest whole-number ratio of atoms. For example, the empirical formula for a compound with 36.1% calcium and 63.9% chlorine is CaCl2.
- Among hydrocarbons, CH4 is an empirical formula, indicating a simple ratio of carbon to hydrogen.
- If the empirical formula is N2O5 and the formula mass is 108 amu, then the molecular formula remains N2O5, indicating no multiple of the empirical composition.
Studying That Suits You
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Description
Test your knowledge with these flashcards covering key concepts from Chemistry Chapter 7. This chapter focuses on chemical formulas, including the representation of elements and compounds. Ideal for students looking to reinforce their understanding of ionic compounds.
