2a • Calculate how many grams are in one mole by multiplying the number of atoms of each element by their mass:
• Multiply this by the number of moles in the sample:
2b • Convert ppm to g per kg:
• Divide by the mass of one mole of calcium:
2c • Convert ppt to g per kg:
• Divide by the mass of sodium:
2d • Convert from ppb to moles per kg:
• Multiply by the flux of water:
3a • Substitute the values for water into the equation:
3b • Substitute the values into the equation:
• Ensure all units are consistent:
4a • Convert 1ml into litres:
• Multiply this by the size of the sample:
4b • Work out the conversion between cm3 and m3:
• Work out the conversion between 1L and 1m3:
• Multiply by the volume of the ocean:
4c • Convert 142 mgL-1 into 142 mgm-3:
• Multiply by the sample size and convert mg to g:
4d • Calculate the number of moles of Mg in the ocean:
• Use the volume of the ocean to work out the overall concentration of Mg in seawater:
5 Note: Brackets around α, β and γ represent their units.
• Because the components are being summed, we know their units must all be equal and equivalent to units of density. Remember α is multiplied by temperature, units K, and γ is multiplied by pressure, units Pa.
• Rearrange the equations for (α), (β) and (γ):
6 Note: Brackets around Qd and k represent their units.
• Because Qd and A.d are being summed, their units must be equal:
• Because you’re adding two components to make T in Kelvin, both components must also have units of kelvin: