Question

For each compound, list the correct formula and calculate the formula mass. (a) tin(IV) sulfate (b) nitrous acid (c) sodium bicarbonate (d) phosphorus pentafluoride

Short answer

a) Sn(SO4)2, 398.718 g/mol; b) HNO2, 47.016 g/mol; c) NaHCO3, 84.007 g/mol; d) PF5, 125.966 g/mol.

Step-by-step solution

Determine the formula for tin(IV) sulfate

Start by recognizing that tin(IV) means tin has a +4 charge, denoted as Sn^(4+). Sulfate is a polyatomic ion with the formula SO4^(2-). Because the charges must balance in a neutral compound, we need two sulfate ions to balance one tin(IV) ion, giving the formula Sn(SO4)2.

Calculate the formula mass for tin(IV) sulfate

To find the formula mass of Sn(SO4)2, add the atomic masses of all the atoms in the formula: 1(Sn) + 2(S) + 8(O). The formula mass is computed as: (1 * 118.71) + (2 * 32.07) + (8 * 15.999) = 398.718 g/mol.

Determine the formula for nitrous acid

Nitrous acid is made of hydrogen (H), nitrogen (N), and oxygen (O). The formula for nitrous acid, which contains one hydrogen, one nitrogen, and two oxygens, is HNO2.

Calculate the formula mass for nitrous acid

The formula mass of HNO2 is found by adding the atomic masses: 1(H) + 1(N) + 2(O). The formula mass is calculated as: (1 * 1.008) + (1 * 14.01) + (2 * 15.999) = 47.016 g/mol.

Determine the formula for sodium bicarbonate

Sodium bicarbonate comprises sodium (Na), hydrogen (H), carbon (C), and oxygen (O). Its formula includes one sodium, one hydrogen, one carbon, and three oxygens, resulting in NaHCO3.

Calculate the formula mass for sodium bicarbonate

Adding the atomic masses for NaHCO3 gives: 1(Na) + 1(H) + 1(C) + 3(O). The formula mass is (1 * 22.990) + (1 * 1.008) + (1 * 12.01) + (3 * 15.999) = 84.007 g/mol.

Determine the formula for phosphorus pentafluoride

The formula for phosphorus pentafluoride indicates one phosphorus (P) and five fluorine (F) atoms, which gives us PF5.

Calculate the formula mass for phosphorus pentafluoride

To calculate the formula mass of PF5, sum the atomic masses: 1(P) + 5(F). The formula mass is then: (1 * 30.974) + (5 * 18.998) = 125.966 g/mol.

Key concepts

Molecular Mass

Understanding molecular mass is crucial for delving into the world of chemical compounds and reactions. It refers to the sum of the atomic masses of all the atoms in a molecule. The atomic mass of an element is given in atomic mass units (amu), which is roughly equivalent to the mass of a single proton or neutron.

To calculate the molecular mass, one needs to know the chemical formula of the substance. For example, in the case of tin(IV) sulfate, the provided formula is Sn(SO4)2. Here, tin contributes with its atomic mass, while the sulfate ions, comprised of sulfur and oxygen, each add to the total mass. The final mass is the one-tin weight plus the mass of sulphur multiplied by two, together with the mass of oxygen multiplied by eight, providing the molecular mass of the compound in grams per mole (g/mol). This serves as a fundamental aspect in chemistry, significantly in stoichiometry, where it aids in determining the proportions of reactants and products in a given reaction.

Chemical Nomenclature

Chemical nomenclature is a systematically uniform way of naming chemical compounds, crucial for scientists to communicate without confusion. For example, tin(IV) sulfate clearly indicates a compound of tin with a +4 charge paired with the sulfate anion. In nitrous acid, the 'nitrous' part means the compound contains nitrogen in a specific oxidation state, which differentiates it from related compounds like nitric acid.

Nomenclature allows us to derive the chemical formula from the name, as seen with sodium bicarbonate (NaHCO3), where each part of the name corresponds to a specific element or polyatomic ion. Learning to decode these names is essential for students so that they can predict the composition and properties of the compound just from its name, tying into other vital chemistry concepts like molecular structure and reactivity.

Polyatomic Ions

Polyatomic ions are charged entities composed of two or more atoms covalently bonded, which function as a single unit in chemical reactions. Familiarity with common polyatomic ions like the sulfate (SO4^(2-)) and bicarbonate (HCO3^(-)) ions is needed to properly assign molecular formulas based on the compound's name, such as in tin(IV) sulfate or sodium bicarbonate.

These ions can significantly change the properties of compounds they partake in, and are recognized by specific nomenclature patterns. For instance, 'ate' and 'ite' at the end of a name typically denote polyatomic ions, with 'ate' generally referring to a higher number of oxygen atoms than 'ite'. Comprehending polyatomic ions enhances your insight into how compounds react during chemical equations, thereby influencing stoichiometry calculations.

Stoichiometry

Stoichiometry is a section of chemistry that involves calculating the relative quantities of reactants and products in chemical reactions. It uses the mole concept and the conservation of mass to ensure that atoms are neither created nor destroyed in reactions. This is where the molecular mass plays an essential role; it allows the conversion of grams to moles, providing a means to quantify the amount of substance involved.

For example, understanding the formula mass of sodium bicarbonate and its conversion to grams helps when determining how much product one can expect from a certain mass of reactants in a baking reaction, where sodium bicarbonate is commonly used. Mastery of stoichiometry is indispensable for anyone studying chemistry, as it enables you to predict the outcomes of reactions and prepare the appropriate amounts of materials for experiments.