Bài 15: Ý nghĩa là cách tính biến thiên Enthalpy phản ứng hóa học
Hướng dẫn giải Luyện tập 2 (Trang 85 SGK Hóa 10, Bộ Cánh diều)
<p><strong>Luyện tập 2 (Trang 85 SGK H&oacute;a 10, Bộ C&aacute;nh diều):</strong></p> <p>T&iacute;nh <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mo>&#8710;</mo><mi>r</mi></msub><mo>,</mo><msubsup><mi>H</mi><mn>298</mn><mn>0</mn></msubsup></math>&nbsp;c&aacute;c phản ứng đốt ch&aacute;y ho&agrave;n to&agrave;n 1 mol mỗi chất C<sub>2</sub>H<sub>4</sub>(g), C<sub>2</sub>H<sub>6</sub>(g), CO(g). Biết c&aacute;c sản phẩm thu được đều ở thể kh&iacute;.</p> <p>&nbsp;</p> <p><strong><span style="text-decoration: underline;"><em>Hướng dẫn giải:</em></span></strong></p> <p>- C&aacute;c phương tr&igrave;nh phản ứng:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi mathvariant="normal">C</mi><mn>2</mn></msub><msub><mi mathvariant="normal">H</mi><mn>4</mn></msub><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>&#160;</mo><mo>&#8594;</mo><mo>&#160;</mo><mn>2</mn><msub><mi>CO</mi><mn>2</mn></msub><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>2</mn><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mspace linebreak="newline"/><msub><mi mathvariant="normal">C</mi><mn>2</mn></msub><msub><mi mathvariant="normal">H</mi><mn>6</mn></msub><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mfrac><mn>7</mn><mn>2</mn></mfrac><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>&#160;</mo><mo>&#8594;</mo><mo>&#160;</mo><mn>2</mn><msub><mi>CO</mi><mn>2</mn></msub><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mspace linebreak="newline"/><mi>CO</mi><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>&#160;</mo><mo>&#8594;</mo><mo>&#160;</mo><msub><mi>CO</mi><mn>2</mn></msub></math></p> <p>- X&eacute;t phản ứng đốt ch&aacute;y 1 mol C<sub>2</sub>H<sub>4</sub>:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi mathvariant="normal">C</mi><mn>2</mn></msub><msub><mi mathvariant="normal">H</mi><mn>4</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>&#8594;</mo><mo>&#160;</mo><mn>2</mn><msub><mi>CO</mi><mn>2</mn></msub><mo>(</mo><mi>g</mi><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>2</mn><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo></math></p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi>CO</mi><mn>2</mn></msub><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>3</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">C</mi><mn>2</mn></msub><msub><mi mathvariant="normal">H</mi><mn>4</mn></msub><mo>)</mo></math></p> <p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mo>&#160;</mo><mo>-</mo><mn>393</mn><mo>,</mo><mn>5</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mo>(</mo><mo>-</mo><mn>241</mn><mo>,</mo><mn>8</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><mn>2</mn><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>3</mn><mi mathvariant="normal">x</mi><mn>0</mn><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>1</mn><mi mathvariant="normal">x</mi><mn>52</mn><mo>,</mo><mn>4</mn><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mo>-</mo><mn>1323</mn><mo>&#160;</mo><mi>k</mi><mi>J</mi><mo>.</mo><msup><mi>mol</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></math></p> <p>- X&eacute;t phản ứng đốt ch&aacute;y 1 mol C<sub>2</sub>H<sub>6</sub>:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi mathvariant="normal">C</mi><mn>2</mn></msub><msub><mi mathvariant="normal">H</mi><mn>6</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mfrac><mn>7</mn><mn>2</mn></mfrac><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>&#8594;</mo><mo>&#160;</mo><mn>2</mn><msub><mi>CO</mi><mn>2</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo></math></p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi>CO</mi><mn>2</mn></msub><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mn>3</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mfrac><mn>7</mn><mn>2</mn></mfrac><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">C</mi><mn>2</mn></msub><msub><mi mathvariant="normal">H</mi><mn>6</mn></msub><mo>)</mo></math></p> <p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mo>&#160;</mo><mo>-</mo><mn>393</mn><mo>,</mo><mn>5</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><mn>2</mn><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mo>(</mo><mo>-</mo><mn>241</mn><mo>,</mo><mn>8</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><mn>3</mn><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mfrac><mn>7</mn><mn>2</mn></mfrac><mi mathvariant="normal">x</mi><mn>0</mn><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>1</mn><mi mathvariant="normal">x</mi><mo>(</mo><mo>-</mo><mn>84</mn><mo>)</mo><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mo>-</mo><mn>1428</mn><mo>,</mo><mn>4</mn><mo>&#160;</mo><mi>k</mi><mi>J</mi><mo>.</mo><msup><mi>mol</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></math></p> <p>- X&eacute;t phản ứng đốt ch&aacute;y 1 mol CO:</p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><mi>CO</mi><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo><mo>&#160;</mo><mo>&#8594;</mo><mo>&#160;</mo><msub><mi>CO</mi><mn>2</mn></msub><mo>(</mo><mi mathvariant="normal">g</mi><mo>)</mo></math></p> <p><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi>CO</mi><mn>2</mn></msub><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><msub><mi mathvariant="normal">O</mi><mn>2</mn></msub><mo>)</mo><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><msub><mo>&#8710;</mo><mi mathvariant="normal">f</mi></msub><msubsup><mi mathvariant="normal">H</mi><mn>298</mn><mn>0</mn></msubsup><mo>(</mo><mi>CO</mi><mo>)</mo></math></p> <p>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><mo>=</mo><mo>&#160;</mo><mo>-</mo><mn>393</mn><mo>,</mo><mn>5</mn><mo>&#160;</mo><mi mathvariant="normal">x</mi><mo>&#160;</mo><mn>1</mn><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mi mathvariant="normal">x</mi><mn>0</mn><mo>&#160;</mo><mo>-</mo><mo>&#160;</mo><mn>1</mn><mi mathvariant="normal">x</mi><mo>(</mo><mo>-</mo><mn>110</mn><mo>,</mo><mn>5</mn><mo>)</mo><mo>&#160;</mo><mo>=</mo><mo>&#160;</mo><mo>-</mo><mn>283</mn><mo>&#160;</mo><mi>kJ</mi><mo>.</mo><msup><mi>mol</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup></math></p>
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