If several reactions take place simultaneously at the electrode a partial electrode current density (c.d.) $j_k$ can be assigned to each reaction. It is given by the stoichiometry of the reaction and by the amount of substance of B reacting (per unit time and per unit electrode area) in the reaction considered. The current efficiency of reaction $k$, $\text{Math input error}$ is defined as the ratio of $j_k$ to the total c.d.: $$\text{Math input error}$$ Note that $\text{Math input error}$ may be larger than one if cathodic and anodic reactions take place simultaneously at the same electrode. However, $\text{Math input error}$ still gives correctly the product yield, which is the quantity of industrial interest. The product yield is the amount of substance of B produced per unit charge and is equal to $\text{Math input error}$ (in the absence of a chemical reaction which is consecutive to the electrode reaction and which consumes or produces species B). $n_k$ is the charge number of electrode reaction $k$. Note that in the case of simultaneous electrode reactions the distribution of the partial c.d. $j_k$ may be different from that of the total c.d., i.e. the function $\frac{{\left(j_k\right)}_{\text{x}}}{j}=f_k\left(x\right)$ may be different from $\frac{j_{\text{x}}}{j}=f(x)$. In electroplating the term 'metal distribution' is sometimes used to designate the distribution $f_k\left(x\right)$ of the partial c.d. for metal deposition.