Sodium hydroxide is the active ingredient in many household products designed to clear blocked drains. Come to and discover math review, adding and subtracting and a large number of additional math subject areas that is, we start with "reactant" and we end up with "product". The order in which we list the products does not matter. If there are 100 cm in every meter, then 3.55 m equals 355 cm. Write a word equation to describe the chemical reaction that Chris demonstrated to the students. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. (c) What is the volume of 11.3 g graphite (density = 2.25 g/cm3)? The name of each product is separated by a plus sign (+) on the right hand side of the arrow. A barrel of oil is exactly 42 gal. Thus, by a more formal procedure, we find that 3.55 m equals 355 cm. For more information contact us at or check out our status page at If I want to list elements I separate two names with "and", for example, sodium and oxygen. *pounds and ounces are technically units of force, not mass, but this fact is often ignored by the non-scientific community. The amount in mL should be 1000 times larger than the given amount in L. The amount in s should be 1/1000 the given amount in ms. To convert a value reported in one unit to a corresponding value in a different unit using conversion factors. A generalized description of this process is as follows: quantity (in old units) × conversion factor = quantity (in new units). hydrogen + sodium hydroxide means that the products of this chemical reaction are the two new substances hydrogen and sodium hydroxide. \( 4.7 \cancel{\rm{L}} \times \dfrac{1 \; \rm{mL}}{10^{-3}\; \cancel{\rm{L}}} = 4,700\; \rm{mL}\) When the chemical reaction was over, and the beaker was cool to the touch, Chris and the students analysed the other product of the reaction and found that it was a compound known as sodium hydroxide. Writing Word Equations for Chemical Reactions . A conversion factor is a factor used to convert one unit of measurement into another. }=\frac{0.030 L}{1 fl oz. The chemical reaction between iron and hydrochloric acid to produce iron chloride and hydrogen can be written in any of the following ways because they all represent the same chemical reaction: iron + hydrochloric acid → iron chloride + hydrogen, iron + hydrochloric acid → hydrogen + iron chloride, hydrochloric acid + iron→ hydrogen + iron chloride. Simply put, it is the conversion between an amount in one unit to the corresponding amount in a desired unit using various conversion factors. (a) what is the mass of 6.00 cm3 of mercury (density = 13.5939 g/cm3)? Missed the LibreFest? In later studies, the conversion problems you will encounter will not always be so simple. Conversions in the metric system, as covered earlier in this chapter. After paying for 3 cards and some stamps, he had $3 left. Please enable javascript and pop-ups to view all page content. Is a 197-lb weight lifter light enough to compete in a class limited to those weighing 90 kg or less? In contrast, conversion factors that come from measurements (such as density, as we will see shortly) or that are approximations have a limited number of significant figures and should be considered in determining the significant figures of the final answer. Equally it tells us that if we were to eat some iron then when that iron reaches our stomach which contains hydrochloric acid, a chemical reaction would occur in which iron chloride and hydrogen would be produced. The use of units in a calculation to ensure that we obtain the final proper units is called dimensional analysis. PROBLEM \(\PageIndex{12}\) Many chemistry conferences have held a 50-Trillion Angstrom (Å) Run. The names of some non-metal elements end in "ine", for example, fluorine, chlorine, bromine, iodine. The students gasped in amazement as the small piece of sodium rocketed around in the beaker, hydrogen gas exploding out of the beaker. General word equation: reactant(s) → product(s). sodium + water → hydrogen + sodium hydroxide. Pharmacists can advise physicians on the selection, dosage, interactions, and side effects of drugs. The calcium carbonate reacts with some of the hydrochloric acid to produce calcium chloride, water and carbon dioxide gas. The product is the new substance that is produced (or made, or formed, or prepared). Therefore the word equation we wrote states that Chris added some sodium to water and produced hydrogen and sodium hydroxide. The names of lots of metal elements end in "ium", for example sodium, calcium, magnesium, aluminium (NOTE that helium is an exception because it is an element but it is a non-metal!). (1 Å = 1 x 10-10 m) Answer 5 kilometers or 3.1 miles. How to Solve Chemistry Word Problems . A simple conversion factor can be used to convert meters into centimeters, or a more complex one can be used to convert miles per hour into meters per second. Consider the description below for preparing barium sulfate, a white solid that is used in medicine (known as a "barium meal"): Barium sulfate can be prepared by adding sulfuric acid to a solution of barium nitrate. Have questions or comments? Counted numbers are also exact. General Steps in Performing Dimensional Analysis. A word equation shows the reactant reacting to produce the product: The arrow in the general form of the equation above shows the direction in which the chemical reaction proceeds: Indigestion is caused by an increase in the acid level of my stomach. or, \( 4.7 \cancel{\rm{L}} \times \dfrac{1,000 \; \rm{mL}}{1\; \cancel{\rm{L}}} = 4,700\; \rm{mL}\), \( 18 \; \cancel{\rm{ms}} \times \dfrac{10^{-3}\; \rm{s}}{1 \; \cancel{\rm{ms}}} = 0.018\; \rm{s}\), \( 18 \; \cancel{\rm{ms}} \times \dfrac{1\; \rm{s}}{1,000 \; \cancel{\rm{ms}}} = 0.018\; \rm{s}\). The label on a box of cereal gives the mass of cereal in two units: 978 grams and 34.5 oz. The reactant is the substance we start with, the substance that is present before the chemical reaction starts. Yes, it does; it has the same quantity in the numerator as in the denominator (except that they are expressed in different units). The order in which we list the reactants does not matter. What is the diameter in centimeters? De-code the word equation you wrote to try to re-create Chris's demonstration. The average volume of blood in an adult male is 4.7 L. What is this volume in milliliters? Identify the "given"information and what the problem is asking you to "find.". Here is what we would have gotten: \[ 3.55 \; \rm{m} \times \dfrac{1\; \rm{m}}{100 \; \rm{cm}} = 0.0355 \dfrac{\rm{m}^2}{\rm{cm}}\]. The names of some non-metal elements end in "on", for example, carbon, neon, argon, krypton, radon. Let's see if we can identify the names of reactants (the substances we start with) in the following description of a chemical reaction: When a piece of zinc is placed in a beaker containing hydrochloric acid, bubbles of hydrogen form on the surface of the metal. The new substances that are produced are called products. It was only after finishing my lunch and experiencing the discomfort of indigestion that I remembered why I never drink fizzy drinks. For the answer to be meaningful, we have to construct the conversion factor in a form that causes the original unit to cancel out. Suppose we divide both sides of the equation by \(1 \text{m}\) (both the number and the unit): \[\mathrm{\dfrac{100\:cm}{1\:m}=\dfrac{1\:m}{1\:m}}\]. A word equation shows the names of the products on the right hand side of the arrow. Perhaps you can determine the answer in your head. A word equation is a short-hand way of describing a chemical reaction. The name of each reactant is separated by a plus sign (+) on the left hand side of the arrow. 2.6: Problem Solving and Unit Conversions, [ "article:topic", "showtoc:no", "transcluded:yes", "source-chem-51021" ], 2.7: Solving Multistep Conversion Problems, Converting Between Units with Conversion Factors. Marisa Alviar-Agnew (Sacramento City College). (d) What is the volume of 39.657 g bromine (density = 2.928 g/cm3)? This chemical equation tells us that if we add hydrochloric acid to iron (a metal) in a beaker in the lab, then they will react to produce two new substances; iron chloride and hydrogen (which is a colourless gas that easily burns).