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
42cubic centimeter are in the block
volume is 48
The molality of the solution is obtained as 0.63 m.
<h3>What is the freezing point?</h3>
The freezing point is the temperature at which the liquid is converted into solid.
We know that;
ΔT = 3.5° C
K = 1.86° C/m
i = 3
m = ?
Thus;
ΔT = K m i
m = ΔT/K i
m = 3.5° C/ 1.86° C/m * 3
m = 0.63 m
Learn more about freezing point:brainly.com/question/3121416
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The answer is: True.
The magnitude of a vector is represented by the length of the arrow.
The arrow length is drawn according a chosen scale.
For example, the diagram shows a vector with a magnitude of 100 kilometers, if the scale used for constructing the diagram is 1 cm = 10 km, the vector arrow is drawn with a length of 10 cm.
The arrow has an obvious tail and arrowhead. The arrow points in the precise direction.