<p>When copper is treated with a certain concentration of nitric acid, nitric oxide and nitrogen dioxide are liberated in equal volumes according to the equation</p>

<p><math xmlns="http://www.w3.org/1998/Math/MathML" class="wrs_chemistry"><mi>xCu</mi><mo>+</mo><msub><mi>yHNO</mi><mn>3</mn></msub><mo>&#8594;</mo><mi>Cu</mi><msub><mrow><mo>(</mo><msub><mi>NO</mi><mn>3</mn></msub><mo>)</mo></mrow><mn>2</mn></msub><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><mi>NO</mi><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><msub><mi>NO</mi><mn>2</mn></msub><mo>&#160;</mo><mo>+</mo><mo>&#160;</mo><msub><mi mathvariant="normal">H</mi><mn>2</mn></msub><mi mathvariant="normal">O</mi></math></p>

<p>The coefficients x and y are</p>