{"id":32446,"date":"2025-06-22T13:57:07","date_gmt":"2025-06-22T13:57:07","guid":{"rendered":"https:\/\/gaviki.com\/blog\/?p=32446"},"modified":"2025-06-22T13:57:09","modified_gmt":"2025-06-22T13:57:09","slug":"while-solving-problems-in-stoichiometry-it-is-useful-to-pay-attention-to-the-units-of-the-answer","status":"publish","type":"post","link":"https:\/\/gaviki.com\/blog\/while-solving-problems-in-stoichiometry-it-is-useful-to-pay-attention-to-the-units-of-the-answer\/","title":{"rendered":"While solving problems in stoichiometry, it is useful to pay attention to the units of the answer"},"content":{"rendered":"\n

Student Exploration: Stoichiometry Gizmo Activity B Check that the equation is still: FeO + 3CO2 -> Fe + 3CO Canceling units Introduction: While solving problems in stoichiometry, it is useful to pay attention to the units of the answer. The process of comparing units is called dimensional analysis. A common technique involves using conversion factors to convert from one unit to another. Units that appear in the numerator and denominator of a fraction can be canceled out. For example, converting 2 moles of carbon monoxide to grams involves multiplying by a conversion factor: 2 mol-CO * 28.01 g CO \/ 1 mol-CO = 56.02 g CO. All conversion factors are equivalent to one. For example, the conversion factor given above is equivalent to one because the numerator (28.01 g CO) and denominator (1 mol CO) represent the same amount of CO. The mol CO unit is canceled, leaving an answer unit of grams. Question: How do we solve problems in stoichiometry? 1. Observe: The first question is: How many moles of carbon monoxide (CO) are required to\u2026 (see, click New question until it appears.) A. What unit is given in the question? moles B. What quantity is asked for? 2. Find: Look for the conversion factor that contains the units mol FeO on top and mol CO on the bottom. Drag the tile containing this factor down to the green strip at the bottom. According to the tile, how many moles of CO react with one mole of FeO? 3. Analyze: To get an answer in moles of CO, you need to cancel the moles of FeO. Turn on Show units. A. What units are given to the right of the equals sign? B. If these aren’t the units you want, click Flip tile. What unit is given now? 4. Calculate: If the units are correct, multiply or divide the numbers to solve the problem. A. How many moles of CO will react with 1.75 moles of FeO? B. Turn on Show numerical result. Were you correct? Activity B continued on the next page<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

Let’s work through the Gizmo Activity B step by step.<\/p>\n\n\n\n

Given:<\/h3>\n\n\n\n

Balanced equation:
Fe\u2082O\u2083 + 3CO \u2192 2Fe + 3CO\u2082<\/strong><\/p>\n\n\n\n

Step 1: Observe<\/h3>\n\n\n\n

Question:<\/strong>
“How many moles of carbon monoxide (CO) are required to react completely with 1.75 moles of iron (III) oxide (Fe\u2082O\u2083)?”<\/em><\/p>\n\n\n\n

A. What unit is given in the question?<\/strong>
Moles Fe\u2082O\u2083<\/strong><\/p>\n\n\n\n

B. What quantity is asked for?<\/strong>
Moles of CO<\/strong><\/p>\n\n\n\n

\n\n\n\n

Step 2: Find the Conversion Factor<\/h3>\n\n\n\n

From the balanced equation:
1 mol Fe\u2082O\u2083 reacts with 3 mol CO<\/strong><\/p>\n\n\n\n

So, the correct conversion factor is:
(3 mol CO) \/ (1 mol Fe\u2082O\u2083)<\/strong><\/p>\n\n\n\n

\n\n\n\n

Step 3: Analyze<\/h3>\n\n\n\n

To solve the problem:<\/p>\n\n\n\n

    \n
  • Start with the given value: 1.75 mol Fe\u2082O\u2083<\/li>\n\n\n\n
  • Multiply by the conversion factor to cancel out \u201cmol Fe\u2082O\u2083\u201d and leave \u201cmol CO\u201d<\/li>\n<\/ul>\n\n\n\n

    A. What units are given to the right of the equals sign?<\/strong>
    Initially: mol Fe\u2082O\u2083<\/strong><\/p>\n\n\n\n

    B. After applying the conversion factor, the units become:<\/strong>
    mol CO<\/strong><\/p>\n\n\n\n

    \n\n\n\n

    Step 4: Calculate<\/h3>\n\n\n\n

    Multiply: 1.75\u2009mol Fe\u2082O\u2083\u00d73\u2009mol CO1\u2009mol Fe\u2082O\u2083=5.25\u2009mol CO1.75 \\, \\text{mol Fe\u2082O\u2083} \\times \\frac{3 \\, \\text{mol CO}}{1 \\, \\text{mol Fe\u2082O\u2083}} = 5.25 \\, \\text{mol CO}1.75mol Fe\u2082O\u2083\u00d71mol Fe\u2082O\u20833mol CO\u200b=5.25mol CO<\/p>\n\n\n\n

    A. How many moles of CO will react with 1.75 moles of Fe\u2082O\u2083?<\/strong>
    Answer: 5.25 mol CO<\/strong><\/p>\n\n\n\n

    B. Were you correct after checking Show numerical result?<\/strong>
    Yes, 5.25 mol CO<\/strong> is the correct and expected answer.<\/p>\n\n\n\n

    \n\n\n\n

    Explanation<\/h3>\n\n\n\n

    In stoichiometry, understanding how to convert between different substances in a chemical reaction is critical. This involves using the mole ratio<\/strong> from a balanced chemical equation. Dimensional analysis helps manage these unit conversions.<\/p>\n\n\n\n

    In this example, the balanced equation tells us that 1 mole of Fe\u2082O\u2083 reacts with 3 moles of CO<\/strong>. That gives us a ratio or conversion factor:
    (3 mol CO) \/ (1 mol Fe\u2082O\u2083)<\/strong>.<\/p>\n\n\n\n

    You start with what is given: 1.75 mol Fe\u2082O\u2083<\/strong>. To find how many moles of carbon monoxide are needed, multiply this amount by the conversion factor. This cancels out the unit \u201cmol Fe\u2082O\u2083\u201d and leaves \u201cmol CO\u201d. 1.75\u2009mol Fe\u2082O\u2083\u00d73\u2009mol CO1\u2009mol Fe\u2082O\u2083=5.25\u2009mol CO1.75 \\, \\text{mol Fe\u2082O\u2083} \\times \\frac{3 \\, \\text{mol CO}}{1 \\, \\text{mol Fe\u2082O\u2083}} = 5.25 \\, \\text{mol CO}1.75mol Fe\u2082O\u2083\u00d71mol Fe\u2082O\u20833mol CO\u200b=5.25mol CO<\/p>\n\n\n\n

    This tells us that 5.25 moles of CO<\/strong> are required to react with 1.75 moles of Fe\u2082O\u2083<\/strong>. Unit cancellation helps ensure the correctness of your approach, and that you end up with the desired unit in the answer.<\/p>\n\n\n\n

    This method is useful for all stoichiometry problems, where quantities of reactants or products are calculated using mole ratios and conversion factors derived from balanced equations.<\/p>\n\n\n\n

    \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

    Student Exploration: Stoichiometry Gizmo Activity B Check that the equation is still: FeO + 3CO2 -> Fe + 3CO Canceling units Introduction: While solving problems in stoichiometry, it is useful to pay attention to the units of the answer. The process of comparing units is called dimensional analysis. A common technique involves using conversion factors […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-32446","post","type-post","status-publish","format-standard","hentry","category-quiz-questions"],"_links":{"self":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/32446","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/comments?post=32446"}],"version-history":[{"count":1,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/32446\/revisions"}],"predecessor-version":[{"id":32449,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/posts\/32446\/revisions\/32449"}],"wp:attachment":[{"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/media?parent=32446"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/categories?post=32446"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gaviki.com\/blog\/wp-json\/wp\/v2\/tags?post=32446"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}