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3

Your qualitative understanding is correct. As you increase the temperature, you have two effects: The dissociation reaction, which is endothermic, shifts to the right. This effect increases the concentration of hydrogen ions. The concentration of hydrogen ions is expressed as molarity, which is number per unit volume. As you increase $T$, water expands, ...


2

For pure water, $\mathrm{pH}=- \frac 12 \cdot \log{K_\mathrm{w}}$. As $K_\mathrm{w}$ grows with temperature, $\mathrm{pH}$ decreases. The influence of water thermal dilation is much smaller than the temperature dependency of water autodissociation constant. For solutions with acids, bases, acidic or alkaline salts, buffering systems it is much more ...


14

The numbers in the code have nothing to do with viscosity index. However, your understanding of 'W' for winter is correct. The real code for your car is actually SAE 5W-30 where SAE stands for the Society of Automotive Engineers, which has established a multi-grade numerical code system for grading motor oils according to their viscosity characteristics. I ...


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