Explanation:
For transfer of heat between any two substances or matter can be occurred by conduction or convection process.
Conduction is a process in which two objects of different temperature are placed in contact with each other. Therefore, heat transfers from hotter object to colder object until the temperature of both objects becomes equal.
For example, a metal spoon placed in a hot cup of tea.
Convection is a process in which a fluid generally liquid or gas is heated and denser material (colder) sinks at the bottom whereas less denser material (hotter) rises at the top. This causes conventional currents in the fluid.
For example, heating rice in a pot full of water.
Answer:
The first row fits in period 2
The second row fits in period 3
Explanation:
Elements arranged vertically in the periodic table in groups that share similar chemical properties.
Elements are also organized horizontally in rows or periods
The length of each period is determined by the number of electrons that can occupy the sublevels being filled in that period.
Answer : The reaction requires 242 grams of HF.
Explanation : Given,
Mass of = 182 g
Molar mass of = 60 g/mole
Molar mass of HF = 20 g/mole
First we have to calculate the moles of
Now we have to calculate the moles of HF.
The given balanced chemical reaction is,
From the balanced chemical reaction, we conclude that
As, 1 mole of react with 4 moles of HF
So, 3.03 moles of react with moles of HF
Now we have to calculate the mass of HF.
Therefore, the reaction requires 242 grams of HF.
Answer:
We need 7.5 mL of the 1M stock of NaCl
Explanation:
Data given:
Stock = 1M this means 1 mol/ L
A 0.15 M solution of 50 mL has 0.0075 moles NaCl per 50 mL
Step 2: Calculate the volume of stock we need
The moles of solute will be constant
and n = M*V
M1*V1 = M2*V2
⇒ with M1 = the initial molair concentration = 1M
⇒ with V1 = the volume we need of the stock
⇒ with V2 = the volume we want to make of the new solution = 50 mL = 0.05 L
⇒ with M2 = the concentration of the new solution = 0.15 M
1*V1 = 0.15*(50)
V1 = 7.5 mL
Since 0.0075 L of 1M solution contains 0.0075 moles
50 mL solution will contain also 0.0075 moles but will have a molair concentration of 0.0075 moles / 0.05 L =0.15 M
We need 7.5 mL of the 1M stock of NaCl
Because it is toxic to humans if absorbed or consumed.