Answer:
We need 1.1 grams of Mg
Explanation:
Step 1: Data given
Volume of water = 78 mL
Initial temperature = 29 °C
Final temperature = 78 °C
The standard heats of formation
−285.8 kJ/mol H2O(l)
−924.54 kJ/mol Mg(OH)2(s)
Step 2: The equation
The heat is produced by the following reaction:
Mg(s)+2H2O(l)→Mg(OH)2(s)+H2(g)
Step 3: Calculate the mass of Mg needed
Using the standard heats of formation:
−285.8 kJ/mol H2O(l)
−924.54 kJ/mol Mg(OH)2(s)
Mg(s) + 2 H2O(l) → Mg(OH)2(s) + H2(g)
−924.54 kJ − (2 * −285.8 kJ) = −352.94 kJ/mol Mg
(4.184 J/g·°C) * (78 g) * (78 - 29)°C = 15991.248 J required
(15991.248 J) / (352940 J/mol Mg) * (24.3 g Mg/mol) = 1.1 g Mg
We need 1.1 grams of Mg
Anything that has mass and volume (takes up space) is called matter.
Answer:
The first one is B, "Decreasing surface area."
Explanation:
This is because greater the surface area exposed, the more collisions that occur between the solvent and solute. I also just took the test myself and got it correct.
Answer:
Molecular compounds consist of two or more nonmetals. The nonmetals that make up a molecular compound are held together by covalent/molecular bonds. Covalent bonds is known as the "sharing" of valence electrons between two or more chemical species. Valence electrons are shared so that the atoms of the compound can become stable, much like how ionic bonds transfer valence electrons between atoms to achieve stability.
