Using a molar heat of combustion of hexane (c6h14) –4163 kj/mol, the mass of hexane required to increase the temperature of 1.76 l of water from 21.0°c to 70.0°c is a. bc g.

put your answer for a. bc in the blank

7.46 g.

Explanation:

Q = m.c.ΔT,

where, Q is the amount of heat absorbed by water (Q = ??? J).

m is the mass of water (m: we will determine).

c is the specific heat capacity of water (c = 4.186 J/g.°C).

ΔT is the temperature difference (final T - initial T) (ΔT =  70.0 °C - 21.0 °C = 49.0 °C).

mass = density x volume.

density of water = 1000 g/L & V = 1.76 L.

∴ mass = density x volume = (1000 g/L)(1.76 L) = 1760.0 g.

∵ Q = m.c.ΔT

∴ Q = m.c.ΔT = (1760.0 g)(4.186 J/g.°C)(49.0 °C) = 360483.2 J ≅ 360.4832 kJ.

Using cross multiplication we can get the no. of moles of hexane that are needed to be burned to release 360.4832 kJ:

Combustion of 1.0 mole of methane releases → - 4163.0 kJ.

Combustion of ??? mole of methane releases → - 360.4832 kJ.

∴ The no. of moles of hexane that are needed to be burned to release 360.4832 kJ = (- 360.4832 kJ)(1.0 mol)/(- 4163.0 kJ) = 0.0866 mol.

∴ mass = (no. of moles needed)(molar mass of hexane) = (0.0866 mol)(86.18  g/mol) = 7.46 g.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.