3 years ago

How is friction harmful?

Chemistry

1 answer:

tekilochka [14]3 years ago

7 0

<span>Friction creates heat which in turn can lead to deviations from the original size and shape of a part.
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Match the following parts of an atom to their description.

Burka [1]

Answer:

Neutron - non charged particle in nucleus

nucleus - composed of proton and Neutron

electron - negatively charged particle that moves around the nucleus

proton - positively charged particle in the nucleus.

Explanation:

these the are definitions of the terms

5 0

2 years ago

Use bond energies to calculate ΔHrxn Δ H r x n for the reaction. 2H2(g)+O2(g)→2H2O(g) 2 H 2 ( g ) + O 2 ( g ) → 2 H 2 O ( g )

Olenka [21]

Answer:

$\large \boxed{\text{-486 kJ}}$

Explanation:

You calculate the energy required to break all the bonds in the reactants.

Then you subtract the energy needed to break all the bonds in the products.

2H₂ + O₂ ⟶ 2H-O-H

Bonds: 2H-H 1O=O 4H-O

D/kJ·mol⁻¹: 436 498 464

$\begin{array}{rcl}\Delta H & = & \sum{mD_{\text{reactants}}} - \sum{nD_{\text{products}}}\\& = & 2 \times 436 +1 \times 498 - 4 \times 464\\&=& 1370 - 1856\\&=&\textbf{-486 kJ}\\\end{array}\\\text{The enthalpy of reaction is $\large \boxed{\textbf{-486 kJ}}$}.$