Answer:
This was important because it supported the concept of discovery of new elements
Explanation:
Mendleev left gaps in his table not discovered at that time, but he predicted the properties (chemical and physical) of undiscovered elements. Mendeleev left the gap next to silicon and named the undiscovered element as 'eka-silicon', the element germanium was discovered later.
Answer:
ΔH° = 840 kJ/mol
Explanation:
Let's consider the following balanced reaction:
2 AgNO₃(aq) + CaCl₂(aq) ⇄ 2 AgCl(s) + Ca(NO₃)₂
Then, we need to know the moles of both reactants:
AgNO₃: n = 0.200 mol/L × 0.0500 L = 0.0100 mol
CaCl₂: n = 0.100 mol/L × 0.0500 L = 0.00500 mol
According to the balanced equation we need 2 moles of AgNO₃ per each mole of CaCl₂, and this coincides with the experimental data, so there is no limiting reactant. Let's use AgNO₃ to find out how many moles of AgCl are produced.
Now, we can calculate the total amount of heat released using the following expression:
Q = c × m × ΔT
where,
c is the heat capacity of the solution
m is the mass of the solution
ΔT is the change in temperature (26.0 °C - 25.0°C = 1.00 °C)
Since the volume is 100.0 mL (50.0 mL + 50.0 mL) and the density is 1.05 g/mL, we can calculate the mass of the solution like:
m = 1.05 g/mL × 100.0 mL = 105 g
Then,
Finally,
Carbon consists of 6 protons and 8 neutrons so the atomic number is 6
Answer:
according to newtons second law
F=ma
mass of the balloon =0.020 kg
gravity = 9.8m/8^2
force = 0.020 x 9.8
= 1.96 N
x (times) hope it helps