All categories

3 years ago

What is the specific heat, thermal conductivity, density of polyurethane foam?

1 answer:

4 0

Insulation materials with higher thicknesses have lower long-term thermal conductivity values in general. The density of rigid polyurethane foam (PUR/PIR) used for building thermal insulation typically ranges from 30 to 45 kg/m3. For some applications, however, it can achieve 100 kg/m3.

You might be interested in

When the bromine atom becomes an anion, it ______ in size.

GenaCL600 [577]

Explanation:

Anions and cations have different atomic sizes than the neutral atoms.

When the bromine atom becomes an anion, it ______ in size.

Anions involves gaining extra electrons. This basically leads to increased repulsion between the electrons and thereby increasing the size. Anions are always larger than the neutral atoms.

This means the answer is A. Increase

When the strontium atom becomes a cation, it ______ in size.

Cations involves losing valence electrons. This basically leads to a decrease in electron shells and electron repulsion thereby reducing the size. Cations are always larger than the neutral atoms.

This means the answer is B. Decrease

3 0

3 years ago

a water sample is found to have a cl- content of 100ppm as nacl what is the concentration of chloride in moles per liter

ladessa [460]

Answer:

The concentration of chloride ion is $2.82\times10^{-3}\;mol/L$

Explanation:

We know that 1 ppm is equal to 1 mg/L.

So, the $Cl^-$ content 100 ppm suggests the presence of 100 mg of $Cl^-$ in 1 L of solution.

The molar mass of $Cl^-$ is equal to the molar mass of Cl atom as the mass of the excess electron in $Cl^-$ is negligible as compared to the mass of Cl atom.

So, the molar mass of $Cl^-$ is 35.453 g/mol.

Number of moles = (Mass)/(Molar mass)

Hence, the number of moles (N) of $Cl^-$ present in 100 mg (0.100 g) of $Cl^-$ is calculated as shown below:

$N=\frac{0.100\;g}{35.453\;g/mol}=2.82\times 10^{-3}\;mol$

So, there is $2.82\times10^{-3}\;mol$ of $Cl^-$ present in 1 L of solution.

5 0

4 years ago

Which has the greater polarizing power, Li+ or Be2+ and why?

kvasek [131]

Answer:

Polarizing power refers to an atoms ability to pull an electron toward it, polarizing the atom the electron comes from. Since cations are positive, they are able to attract electrons toward themselves. Anions are negative and so do not attract more electrons.

Therefore, Be2+ has a higher polarizing power because it has a higher quantitiy of protons, hence a higher polarizing power.

4 0

3 years ago

A chemist determined by measurements that 0.030 moles of barium participated in a chemical reaction. Calculate the mass of bariu

schepotkina [342]

Answer: 4.1 g of barium precipitated.

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar Mass}}$

Given : moles of barium = 0.030

Molar mass of barium = 137 g/mol

$0.030=\frac{x}{137}$

x= 4.1 g

Thus there are 4.1 g of barium that precipitated.

3 0

3 years ago

What is the zeff of carbon ??????<br>plz bata do

nasty-shy [4]

Answer : La carga nuclear efectiva (Zef) es la carga positiva neta experimentada por un electrón en un átomo polielectrónico. El término "efectiva" se usa porque el efecto pantalla de los electrones más cercanos al núcleo evita que los electrones en orbitales superiores experimenten la carga nuclear completa

Explanation:

3 0

3 years ago