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
<span>Japan began its invasion of China in 1931. The Japanese military had their way over the armed forces of China, and occupied parts of China important to their war aims.</span>
There are two kinds of mixtures
a) homogeneous : the boundary of the two components is not physically distinct
b) heterogeneous:the boundary of the two components is physically distinct
the following separation techniques are common for mixtures
1) filtration: if the two components are forming heterogeneous mixture we can separate them by filtration.
2) boiling: if boiling point of one of the components is less than other
3) magnetic separation: if one of the component is magnetic
4)sieve method: for solid components with difference in size of particles
5) hand picking
Thus the correct match will be as shown in the figure
The hotter it gets, the faster molecules move, solid form is in low temperature, liquid in medium temperature and gas in high temperature.
Hello!
The number of 20-g ice cubes required to absorb 47 kJ from a glass of water upon melting is 7 icecubes
Why?
We are going to clear from the equation of the released heat, the mass of ice (m). The specific latent heat of fusion of ice is 336 kJ/kg:

So, 7 ice cubes are required to absorb that amount of heat from the glass of water.
Have a nice day!