À l'aide des documents, dire si l'eau oxygénée peut mettre en évidence une tache de sang et décrire ce que doit observer Justine si elle en applique sur la tache. S'appuyer sur des équations d'oxydoréduction pour étayer vos propos.

A formula connecting density \( (d) \), mass \( (m) \) and volume \( (v) \) is \[ d=\frac{m}{v} \] \( m=30.14 \mathrm{~g} \) after being truncated to 2 d.p. \( v=3.78 \mathrm{~cm}^{3} \) after being truncated to 2 d.p. Calculate the lower and upper bounds of \( d \). Round your answers to \( 2 \mathrm{~d} . \mathrm{p} \).

A chemist carefully measures the amount of heat needed to raise the temperature of a 510.0 mg sample of a pure substance from \( 2.9^{\circ} \mathrm{C} \) to \( 23.7^{\circ} \mathrm{C} \). The experiment shows that 25.9 J of heat are needed. What can the chemist report for the specific heat capacity of the substance? Be sure your answer has the correct number of significant digits.

If 82 g of sugar is dissolved in 7950 mL of water, what is the concentration of the solution?

A chemist carefully measures the amount of heat needed to raise the temperature of a 197.0 g sample of a pure substance from \( 49.4^{\circ} \mathrm{C} \) to \( 67.7^{\circ} \mathrm{C} \). The experiment shows that 16.9 kJ of heat are needed. What can the chemist report for the specific heat capacity of the substance? Be sure your answer has the correct number of significant digits.

A partir de la siguiente ecuación de combustión de octano, si reaccionan 59.2 gramos de octano, ¿Cuántos gramos de Oxígeno se necesitan? \[ \mathrm{C}_{8} \mathrm{H}_{18}+25 / 2 \mathrm{O}_{2}-\cdots>8 \mathrm{CO}_{2}+9 \mathrm{H}_{2} \mathrm{O} \] Considera: \( \mathrm{C}: 12, \mathrm{O}: 16, \mathrm{H}: 1 \)